I see the point of your question.
The Bible considers homosexuality as the worst evil in humankind, far worse than rape, murder, etc.
So, your logic is: If a society legalizes homosexuality, then that society should legalize lesser crimes, too.
Your point brings out the crime against God of so-called evangelical Christians supporting gay marriage laws, because they want to “love homosexuals”. You are saying that by that principle, murder should be legalized, too, since you should “love murderers.”
Your question actually makes logical sense.
It highlights how so-called evangelical Christians have been influenced by the world and they have been brainwashed by the world in a twisted concept of love that does not jive with the Bible.
God wants capital punishment for murderers, and God certainly want capital punishment for homosexuals. Obviously, homosexuality is a worse crime in the Bible than murder is.
That must not be forgotten.
In modern humanistic culture that has been shaped and molded by Political Correctness, anger itself is seen as evil or prosecutable. Thus, some preachers in TV portray Jesus Christ as never having become angry. This is certainly untrue, of course. Anyone who reads the Bible can see that Jesus Christ was angry often. Unfortunately, many people follow the humanistic values of the world, rather than the Bible. Thus, there are many wrong portrayals of Jesus Christ, which is evident in light of the Bible itself. Jesus Christ was often angry, especially at the leaders of Judaism, like the Pharisees and the Sadducees. But Jesus Christ is God. Maybe it’s okay for Christ to be angry, but not okay for His followers to be angry? This is a question that is asked by some of you. Is it okay to be angry or is anger itself wrong for human beings? Bible never condemns anger. In the Gospels, Jesus Christ never condemns anger, either. In fact, Jesus Christ is careful to distinguish between anger that is not justified and anger that is justified. Christ condemns anger that has no righteous cause. In Matthew 5:22, Jesus Christ says: “But I say to you that whoever is angry with his brother without a cause shall be in danger of the judgment.” It is wrong to be angry with someone without a cause, which is justified. But it is okay to be angry with someone for a justifiable cause. Thus, Christians who are angry with the Senate for not defunding Planned Parenthood would be justified in their anger, since abortion is murder of babies. Have a look at the anger shared by Donald Trump, who is running for US President in 2016: http://www.cnn.com/2015/08/04/politics/donald-trump-government-shutdown-planned-parenthood/