Why is That a Sin?

We just came off of what many call, Pride Month. We continue in our "Anything Goes," series looking at exactly why so many of the things celebrated during Pride Month, including homosexuality, same sex marriage, transgenderism, drag, and others are a sin. What are the exact biblical reasons that God has given us that these things are a sin? And why is ignoring them, refusing to speak up about them, or thinking they aren't that bad almost as sinful as the acts themselves?