"Hashem answered Moses, 'I Shall Be As I Shall Be.'" Shemos 3:14.
It is fitting to show proper respect for the Names of the Creator of the Universe. Jewish law outlines the proper respect we must show. The primary Name of G-d is known as the "Shem Havaya". It is spelled with a Yud which is followed by the letter Hei and then follows the letter Vav and then concluded by another letter Hei. This Name is only pronounced phonetically in the Beis HaMikdosh. That means that one does not pronounce this Name unless one is participating in the appropriate service in the Beis HaMikdosh.
When we pronounce this Name we should have in mind that G-d is eternal and self sufficient. Out side the Beis HaMikdosh the Name is pronounced identical to the Name "A-d-o-n-o-y". This is not merely a substitute, rather it is the way to pronounce the Name outside the Beis HaMikdosh. In general when halachic literature refers to the Name it means spelled as above and pronounced as "A-d-o-n-o-y. Therefore when we pronounce this Name we should also have in mind that G-d is Master of all.
One should take care to properly pronounce the Name. One should accent the last syllable (mil'ra). Ashkenazi minhag pronounces the vowels 'patach' differently than the 'qametz', therefore one must make sure to articulate the 'qametz' rather than a 'patach' in the last syllable. Otherwise one will say "adonai" rather than "A-d-o-n-o-y". Care also must be taken not to drop off the final 'yud'. However if the Name follows the Name "A-d-o-n-o-y" as spelled it is pronounced as the Name "E-l-o-h-i-m" instead.
We only say the Name (again this refers to the pronunciation outside the Beis HaMikdosh) under the appropriate circumstances. These include when making a b'rachah, either from the Siddur or during private prayer. One may do so while verbally reading Torah (including Nach and the Talmud). And one may pronounce it while teaching or assisting someone learning a b'rachah. When we are not involved in such activities we say "HaShem" (THE Name) in place of the Shem Havaya.
Other Names of G-d which we show such respect are "A-d-o-n-o-y" (which is typically how we pronounce HaShem, the Shem Havaya, as explained above), "E-l-o-h-i-m", "E-l", "E-l-o-h-e-i-n-u", "E-h'-y-e-h" (see Shemos 3:14), "S-h-a-d-a-i", and "T-z'-v-a-o-s". One must not say them unless engaged in an activity described in the above paragraph. Otherwise one says "Hashem", "Eloqim", "Qel", "Eloqeinu", "Shakai", and "Tz'vakos" respectively.
One must cover one's head with a hat when one recites G-d's Name. One should always cover one's head, and not walk six feet without a head covering. The covering should cover the majority of one's head, although according to some it is sufficient if the covering will remain on one's head unassisted. Traditionally Jews wear a Yarmulke for this purpose.
One should be careful only to recite G-d's Name in an appropriate place. One should not mention G-d's Name in a bathroom or bathhouse. Likewise one should not greet his fellow "Shalom" since this is a Name of G-d. One should not recite G-d's Name in the presence of human feces or urine or a dirty diaper. Similarly not around feces of an animal which produces a foul odor, or any other foul odor.
One should not say G-d's Name in the presence of nakedness as defined by the laws of tznius. Even if one closes ones eyes this is not sufficient. Rather one must be facing the opposite direction. There are more particulars on this matter. Furthermore one may not recite G-d's Name in the presence of one's own nakedness, i.e. when one is wearing a loose fitting garment that doesn't separate the lower body from the upper body. Most styles today, such as pants, fit tightly around the waste and therefore create such a separation. However some have the custom to go further and create such a separation using a special belt for the purpose referred to as a gartel. Women need not be concerned with such a separation but they may not recite G-d's Name when she is not dressed tznius or in front of another woman who is not.
"You shall not take the Name of HaShem, your G-d, falsely." Shemos (Ex) 20:7.
This verse teaches us that we are forbidden to use G-d's Name to make an oath that is either unnecessary or false. The world "Shav", "falsely" or "in vain", is the word used in Hosea 10:4, "They have spoken words, swearing falsely (shav)."
We also learn not to say a Name of G-d when in is unnecessary. This includes any mention of G-d's Name other than during prayer, study, or education as discussed above. One who realizes that he has said G-d's Name without purpose should indicate he has respect for G-d's Name by immediately saying, "ברוך שם כבוד מלכותו לעולם ועד" (blessed is His Name whose glorious kingdom is for ever). If one has begun to say a b'rachah needlessly and has recited the Name HaShem but has yet to continue they may correct the situation by completing the pasuk in T'hillim 119:12 (ברוך אתה ה' למדני חקיך ).
"You shall utterly destroy all the places where the nations that you are driving away worshiped their gods: on the high mountains and on hills and under every leafy tree. You shall smash their pillars; and their sacred trees shall burn in the fire: their carved images shall you cut down; and you shall obliterate their names from that place...You shall not do this to HaShem, your G-d." Devarim (Dt.) 12:2-4.
From these verses we derive the prohibition of destroying sacred objects. In particular we are forbidden from erasing or otherwise destroying one of G-d's Names.
It is therefore forbidden to write one of HaShem's Names on an item or document that will be placed in the garbage. Sacred texts which contain HaShem's Name must be buried in a Jewish cemetery once they become unfit for use. Erasing G-d's Name from a computer screen does not violate the prohibition of destroying G-d's Name but many are careful to not write it out unless it’s necessary.
If one of HaShem's Names is written out by an idol worshiper, it is to be burnt.
"So shall you say to the Children of Israel, 'HaShem the G-d of your forefathers, the G-d of Abraham, the G-d of Isaac, and the G-d of Jacob has dispatched me to you. This is My Name forever, and this is my remembrance from generation to generation." Shemos 3:15.
As we have seen from the above, the Divine Name is extremely holy. This is particularly true of the peculiar Name of G-d, the four letter Name. Unlike the other names of G-d, like "E-l-o--h-i-m", which may refer to other powers or authorities, Hashem is only used in reference to G-d. It is the most common term for G-d in the T'nakh, appearing on almost every page.
Since this Name is so Holy, and the Name used to distinguish the true G-d from the false idols, many have thought it appropriate to use this Name when they reference G-d. More particularly, they reason that it is appropriate to address Him with the Name as it is spelled, according to the pronunciation of the four Hebrew letters that makes up this Name.
After all they reason, it says "This is My Name forever, My remembrance etc." How is it correct to substitute This Name, with "L-rd" as is done by most translations, both Jewish and Christian.
"An Altar of earth shall you make for Me...wherever I cause My Name to be remembered I shall come to bless you" Shemos 20:21
This assumption does not consider the majority of evidence however. The Divine Name of HaShem was never meant to be pronounced as it is spelled on a regular basis. Earlier we read that Hashem is a "remembrance", from which some conclude it should be pronounced as spelled. However we see above that G-d causes His Name to be remembered in particular places. More specifically these places are associated with the sacrificial altar.
We see this association between G-d's Name and the Beis HaMikdosh (i.e. where the altar was) continued throughout the T'nakh. When Yisrael entered the Land in began to disperse themselves, Torah allowed them to offer sacrifices (and erect altars) at various locations. This was, however, a temporary institution. One day, when Yisrael was at peace, Hashem would choose a place that were all sacrifices where brought. Private altars would then become forbidden. The Torah calls this the place HaShem "will choose to rest His Name" (Devarim 12:11). Why is this term used? It is the place where HaShem decrees His Name to be pronounced according to its spelling.
Nor is this the only time such an association mentioned. We see many other such terms used. (2 Shmuel 7:13), "It was in the heart of my father David to build a House for the sake of the Name of Hashem, G-d of Israel...It has been in [David's] heart to build a House for My Name." (M'lachim 1 18:17,18). "I have sanctified this House that you have built, to place My Name there forever" (ibid 9:3). And there are other such examples.
Jewish Law and tradition makes this point clear. Hashem's name was never pronounced outside the Beis HaMikdosh. Outside the Beis HaMikdosh the Name was always pronounced A-d-o-n-o-y. In Jewish Law, this pronunciation has the status of G-d's Name in every regard and when halachah speaks of G-d's Name it always means written with the four letters and pronounced as mentioned (except of course halachos dealing with how it is used in the Beis HaMikdosh).
The Mishnah clearly expresses disapproval of pronouncing HaShem as spelled.
"And these are the one's who have no share in the World to Come...Abba Saul says, ‘Also, he who pronounces the Divine name as it is spelled" Mishnah Sanhedrin 10:1.
Rambam explains those times when it was appropriate for the Name to be pronounced as spelled.
"This Sacred Name, which, as you know, was not pronounced except in the Sanctuary by the appointed priests, when they gave the sacerdotal blessing [Bircas Kohanim], and by the highpriest on the Day of Atonement" Rambam, The Guide for the Perplexed LXI He then explains that it was never known among the common population.
"It was not known to everyone how the name was to be pronounced, what vowels were to be given to each consonant, and whether some of the letters capable or reduplication should receive a dagesh. Wise men successively transmitted the pronunciation of the name, it occurred only once in seven years that the pronunciation was communicated to a distinguished disciples" Ibid LXII
Rashi explains that the prohibition is derived from the verse we discussed above.
"'In every place where I cause my name to be mentioned' Where I give you permission to mention My Ineffable Name, there 'I will come unto thee and bless thee' (i.e.) I will cause My Divine Presence to rest upon thee. Hence you learn that permission was not given to mention the Ineffable Name save where the Divine Presence comes, and that is the Temple there permission was granted to the priests to mention the Ineffable Name at the 'lifting of the hands' to bless the people' (Sota 38)" Rashi on Ex. 20:21.
Jewish Tradition on this subject is loud and clear, and thoroughly based on the T'nakh.
Despite the clarity with which Jewish tradition speaks on this, there is some confusion among some. Some have the impression that the use of the name was gradually was phased out, out of fear of violating the prohibition of taking G-d's Name in vain. This is, as we have discussed, a very important command not to take false oaths and use HaShem's Name to make others believe them. By extension we also learn that we should never use HaShem's Name needlessly, but only during prayer and learning. This all applies to the Name as we actually pronounce it, A-d-o-n-o-y, and not the reason we pronounce it as such. The reason we substitute it is as given above.
The source, in part, of this confusion is a tradition recorded in the Talmud of the use of the Divine Name (as pronounced) in the Beis HaMikdosh. As we mentioned, the Name was only pronounced as spelled in the Beis HaMikdosh during the Bircas Kohanim and the Yom HaKippurim service. Eventually the Name wasn't used even in the Bircas Kohanim in the Beis HaMikdosh because of heretics copying it. Whether you agree with their intentions or not (I generally assume Chazal had a better grasp of the situation than myself or anyone who would wish to challenge the decision nevertheless) it has no relevance to the use of the Name outside the Beis HaMikdosh.
One should not assume that the appearance of HaShem indicates that it was pronounced the way it was written. For example much of the Siddur contains the Name Hashem, but it was put there with the understanding that it would be substituted with A-d-o-n-o-y. Similarly based on the evidence found in the Bible and Jewish tradition, the fact that it is spelled one way in the T'nakh doesn't change the fact it was intended to be pronounced as A-d-o-n-o-y. Those who say otherwise are only showing their bias, ignoring the evidence in Torah and tradition and holding a position based on assumption rather than evidence.
For Those Who Do Try to Pronounce the Name HaShem
Typically for this site the fact something is forbidden by halachah makes it case closed. And most Jews who don't necessarily follow halachah, an ancient tradition of abstaining from pronouncing the Name is reason enough not to. However we see an increasing number of Christians, particularly Messianic Christians, who find the need to try and use HaShem's Name as it is spelled. People such as these don't necessarily put any importance on [Orthodox] Jewish tradition (although the Biblical evidence should cause them some concern).To them, I offer a few reasons that they should reconsider. The fact is that this is not strictly an "Orthodox Jewish Practice" it was the universal Jewish practice. It was practiced by all ancient Jewish sects indicating it dated from a time which preceded the division of those sects. This implies that it dates back to Biblical times and was always the practice as I have suggested.
One of the most ancient manuscripts of the Bible, namely the Isaiah text found among the Dead Sea Scrolls, has the Hebrew word "lord" written above the Name HaShem indicating that the reader substitute it. This is proof that the custom is a least older than Christianity.
The Greek Testament, the Christian Bible, never uses the Name HaShem as it is pronounced. When it cites the T'nakh it uses the Greek word "kurios" when translating the Divine Name. It does not transliterate the Name (put it into Greek characters so that one can pronounce it) even though it transliterates other words like "Satan" of "Abba".
Matthew records an incident where Jesus reads from Isaiah in the Synagogue. The portion included the Name Hashem but, as we mentioned, the word "kurios" is used and there is not recorded uproar caused by Yeshu reading the Name as it is spelled.
In short, even a Christian should think twice before trying to recite G-d's Holy Name as it is spelled. For most of us, the early Christian practice regarding reciting HaShem's Name is irrelevant. It is relevant to those who are most likely to use it though so I decided to include this final section.
Likewise the academic world should reconsider its use of the term. It makes no sense to use a term to designate the G-d of the Jews when 99% or more of Jews throughout history ever used this Name.
One last note, Hebrew has no letter "J". Therefore the insistence of some groups on using the English rendition of the Divine Name "J-e-h-o-v-a-h" is silly as well as misguided. This absurdity is a result of the use of the vowel points of "A-d-o-n-o-y" to indicate to the reader to substitute that Name rather than pronounce it as spelled. Then the yud, "Y", is exchanged for a "J", common when transferring Hebrew Name to English. The result is something that bears little resemblance to the Divine Name but arrogantly proclaimed to be the Divine Name. Even the best known champions of this "name", the Watchtower Society (J. Witnesses), recognize that this is how this "name" came to be. They argue that what counts is really using a personal name to identify G-d, but rather what matters is treating G-d's Name with the proper respect indicated by the Torah and tradition dating back to Biblical times.