Like or not, these people, as horrible as they are, are actually obeying the Bible. The Bible tells people to do these things, its just that (thankfully) most Christians ignore parts of the Bible that they don't like (Fact: Most Christians haven't even read their Bible cover to cover).
These are the "fundamentalist" Christians, who are very bad people. They are not to be mistaken for the moderate, reasonable Christians, who are, on the whole, quite nice people (at least from what I've seen).
But if you REALLY believe in the Bible (and I do NOT), their logic is impeccable. If God really did destroy Sodom and Gomorrah (and all the babies and kids within) for man-on-man action, then he might have been responsible for 9/11. Remember, if you read your bible (and I suggest you do even if you don't believe in it - wait, read it ESPECIALLY if you don't believe in it), God kills many, many people for the actions of a few bad men.
You know the story of Jericho? God didn't like Jericho, so he apparently destroyed the walls and ordered the good, wholesome Israelites to KILL ALL THE CHILDREN, OLD MEN, AND WOMEN AND ANIMALS AND BABIES within the city. Go ahead, read it. Read the Old Testament. He also destroyed the entire world with a giant flood. He also later killed thousands of Israelites and caused them to lose wars because one soldier took some gold that was supposed to go to God's private treasury. God was satiated by burning the soldier alive.
You might say, "Oh, it's just the OLD testament". Well, it's still in your Bible. The part about hating gays is in the Old Testament too. So are the 10 commandments. You can't pick and choose without being illogical.
Thankfully, many Christians don't take their religion seriously, and are perfectly fine, good people who don't believe in that bronze age nonsense written by sexist, angry old men in the desert (which is why God is depicted as being male and why the Bible calls for women to submit to men). Yes, thankfully, the vast majority of Christians are not like the Westboro Bapist Church, who are the real face of Christianity, and they were the norm about 100 years ago. Go back about 100 years, the views of the Westboro Baptist Church was what the Church preached.
"Oh" you say "that was back THEN". Well, if your Bible is the word of God, the immutable, PERFECT WORD OF A SO-CALLED PERFECT GOD, then you have to obey everything in the Bible.
And you say "well, science changes its mind too" - yes, but Science is a human effort, by humans. We make mistakes and we correct them. The Bible is supposedly divine and perfect. And if it's not, then isn't religion just another man-made cultural artifact? I think it is, and I think that, deep down, most Christians know that too. Otherwise they would be just like the Westboro Baptist crazies.
And once again, most Christians are not. Because they are intelligent enough to not really take the Bible seriously.