That's not the main reason. The book of Jude (as well as the text of Genesis 19) makes if very clear Sodom was destroyed for unnatural sexual immorality.
...that depends on the scripture... but the verdict is in—it’s interesting!
The book of Jude is interesting all by itself. Read it, and then read II Peter. They both borrow from the apocryphal work, “The Book of Enoch,” also called, “The Book of the Secrets of Enoch.”
In fact, because of these two books, the canon was extended (with much disagreement) into the early part of the second century. Beyond that, “John” was the last book written, some say as late as 95- 100 AD. Of course, the disagreement was over the fact that these two books quoted from an apocryphal work and how …
Anyway, Jude uses the Greek word ‘porneo,’ which is where we get the word ‘pornography’ from, as well as the word ‘fornication,’ which simply means, sexual intercourse outside of marriage. If one or both are married, it’s adultery, a specific type of fornication.
The next phrase is, “having gone after ‘sarkos eteras,’” meaning, “different flesh.” In the context of porneo, it is most likely referring to bestiality, although, once you go there, it’s merely quibbling as to whether or not that includes homosexuality. The NIV renders it “perversion.”
Genesis 19 is less clear as to why Sodom and Gomorrah and the surrounding ‘cities on the plain’ were destroyed. All we really know is that after Abraham haggled with God, there were less than ten righteous people living in the area. Assuming Lot, his wife and two daughters were in that number, including the men pledged to marry Lot’s daughters, there were, indeed, less than ten. The sin or specific reason for the destruction, however, is not specified.
Genesis 19 also makes clear that God was determined to destroy the two cities before the men of these cities even tried to rape the two angels. As jdlevy95 correctly states, the incident is “adjunct.”
But it is indicative of the evil that these men labored at.
Anyway, Ezekiel 16:48-50 gives the most complete accounting as to why, at least, Sodom was destroyed. No specific sexual sin is mentioned, but the use of the term ‘detestable things,’ is added at the end; kind of a catch-all that conjures up all the detestable things that the people living in Canaan were up to before Israel came in and conquered it. Basically, they were vomited out of the land because of their ‘detestable practices.’
Anyways, here’s a good article on the detestable practices of the nations prior to God’s intervention through his children. I believe the source is Catholic, but the author is Jewish? Oy Vey! What do I know? It’ a good read though.
http://www.catholiceducation.org/articles/homosexuality/ho0003.html