A person on fb told me I was ridiculous because when I write G-d or L-rd I leave out the o. I was told to respect the Name. Is this incorrect? This is a Christian person.
There is no need to leave out the “o” from Lord. For G-d, some halachic authorities rule that the “o” should be left out, because this is the English for the basic reference to Hashem (G-d). Out of respect, meaning to ensure that it should be treated with disrespect (for instance, to ensure that the paper on which it is written is not taken into the bathroom), the “o” is omitted.
Note that the prohibition of erasing the Name of Hashem does not apply to words in other languages, according to the majority of halachic authorities.
The above is based on principles of Jewish Law. For a non-Jew, there is certainly no need to be stringent in this regard, and because it looks strange to many readers, it might be more respectful to write the word in full.
Sources: See Shach Y.D. 179:11; Mishnah Berurah 85:10.