Do you have some proof? The name of God seems to be fully spelled out in holy writings. Strong's Concordance shows no evidence for leaving out the "o" in God for the number 0430. 
Do you have some proof? The name of God seems to be fully spelled out in holy writings. Strong's Concordance shows no evidence for leaving out the "o" in God for the number 0430.
A few citations are included below, if you really want to run them down
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shamash.org: Writing: Why do some people write "G-d" with a hyphen instead of an `o'?
Based on the words in Deut. 12:3-4, the Rabbis deduced that it is forbidden to erase the name of G-d from a written document. Since any paper upon which G-d's name was written might be discarded and thus "erased", the Rabbis forbade explicitly writing the name of G-d, except in Holy Books, with provisions for the proper disposal of such books.
According to Jewish Folklore, G-d has 70 names. However, only one of these names is the ineffable name, which cannot be erased or pronounced. Further, of the 70 names, seven may not be erased but they can be pronounced on certain occasions (such as when reading the Torah). The other names may be erased and pronounced, but still must be treated with respect. The Talmud (Shevuot 35a-b) makes it clear that this prohibition applies only to seven Biblical names of G-d and not to other names or attributes of G-d, which may be freely written. The prohibition was later codified by Maimonides (Mishneh Torah, Yesodei HaTorah 6:1-2). The practice of writing "G-d" is supported in Shut Achiezer, 3:32, end, where it is endorsed and accepted as the prevailing custom. Rambam cites Deut. 12-03:04, which states "and you shall destroy the names of pagan gods from their places. You shall not do similarly to G-d your Lord." The intent of this is to create an atmosphere of respect for G-d's name vs pagan gods names.
As a result of this, people acquired the habit of not writing the full name down in the first place. Strictly speaking, this only applies to Hebrew on a permanent medium, but many people are careful beyond the minimum, and have applied it to non-Hebrew languages. Hence, "G-d". One explanation is that using G-d is a reminder that anything which we may say about G-d is necessarily metaphorical. Spelling out the Name (even in a language other than Hebrew) would imply that one could speak meaningfully (not just metaphorically) about G-d.
However, the Shach (Yoreh De'a 179:11) ruled that "God" spelled in a foreign language does NOT have the status of a "shem" and thus may be erased, lehatkhila. There is a story about Rav Soloveitchik (z"l) intentionally writing GOD on the board while teaching a class and then just as deliberately and intentionally erasing it, so as to demonstrate by his own example that this was not a halakhically a problem.
Conservative ref: http://communities.msn.com/JudaismFAQs&naventryid=160)
and Reform practice is to use "God". However, even some who are not strict (or even observant) in general will write "G-d", to emphasize that Jewish conceptions of G-d are meant.
Note: There is one exception to the destruction of G-d's name. In Numbers 6, the Suspected Wife Ceremony, a man who suspects his wife of adultery (with witnesses seeing a forbidden seclusion) brings his wife to the temple. The Priests test the women by pronouncing the horrible Biblical curse. After reading the curse it is written on parchment and dissolved in water (which the women drinks). If she is guilty she dies and otherwise the couple gets their marriage back. Thus, G-d actually allows the ineffable name to be dissolved in water that the women drinks. As the Talmud notes: G-d allows the ineffable name to be erased for the sake of bringing peace between a husband and wife.
Note that if you disagree with another poster's decision to omit or include the hyphen, you should not publicly criticize or ridicule said poster.
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You can find a brief Reform answer at http://uahc.org/ask/god_questions.shtml
Clearly, they’re all based on Deut 12:3-4. I don’t have a lot of interest in arguing the validity of the position here, I was simply noting some references in response to your request, and implicaton ( It's a time-honored activity spanning millennia…responseDo you have some proof? that this is a recent practice, which it isn’t.
As the response noted, the hyphenated version is not used in Holy Books, which would be consistant with your experience The name of God seems to be fully spelled out in holy writings. Strong's Concordance shows no evidence for leaving out the "o"…, not evidence that this is somehow a recent invention.
You got the point, though you don't know it. Holy books are holy books, and they are treasured and not dscarded without respect. The tradition is to not put God's name on writings that are temporary and informal, not to be kept, that will be thrown away.
It is like the truists regarding the American flag, those who think it is improper to put the image of the flag on items of clothing or other treatment that will not treat that image with the respect a flag should have. Not all patriots follow that etiquette to the letter, feeling proud to wear the flag on a bandana or a shirt... But some do follow it, and their failure to not wear a flag shirt is not a failure to be a good patriot by any stretch. Same with the writing of the word G-d.
HF