Dear DB,
Evolution can mean many things. There are some aspects of evolution that are quite compatible with Church teaching. For more on this, see:
catholic.com/thisrock/2004/0401bt.asp
Your take on gay marriage needs more thought. By discrimination, I assume that you mean racial discrimination. Certainly, there are situations when we are required to discriminate, e.g., between what is good and what is bad.
Simply being discriminating is a good thing. However, discriminating against someone’s basic rights is very much a bad thing. Do you think that people have a RIGHT to marry within their own sex? Do you also think that brothers and sisters have a right to be able to get married—or uncles and nieces, or mothers and sons? These are all instances of people who could say that they loved each other. Is saying that they love each other enough?
The situation of discriminating against persons because of their race is quite different from not recognizing marriages between people of the same sex. Natural law reveals the difference to us. Natural law is a sense of good and evil that is written on the heart of every person. It tells us which acts are good and rational and which are evil and irrational. Natural law tells us that not every kind of behavior is a right. The act of murder is not a right; nor is incest. These go against human nature. We inherently know that these are wrong.
If, for example, many people began telling us that incest is a right and that to deny such a right is similar to discrimination because of race or sex, our first reaction would be moral outrage. For a parent and child to have sexual relations with one another violates the very nature of who they are in relation to one another. Something is out of sync.
Eventually we might be swayed by such argumentation because of the sheer volume and intensity of the propaganda—but not because of the rationality of the argument. This is what has happened with the so-called right to homosexual “marriage.” For two members of the same sex to have genital relations violates the nature of who they are in relation to one another. Their bodies are simply not designed for it. Something is out of sync.
The problem is that in our culture we tend to put feelings before right reason. Reason would tell us that in such a situation, one ought to put feelings second. For rational creatures to make reason subject to feelings is to court disaster.
Before considering whether to leave the Church, you need to learn a lot more about what it teaches and why. You are in my prayers, DB. The Lord has brought you into His Church. It was His idea. You need to think more than twice about this before you consider throwing it over in the face of opposition from the media and prevalent popular secular opinion.
Fr. Vincent Serpa, O.P.