What did sin ever do to God to make Him hate it so much, and why did Jesus feel He had to come here to save us from it? (What's so "bad" about sin?)
Another fair question. Does God hate sin because it makes Him look bad? What's wrong with having a little "fun" now and then? It doesn't hurt anyone, does it?
Actually, yes it does hurt someone. Sin is the breaking of one of God's laws and sin eventually will kill anyone who sins. In fact, sin caused the death of the only Person on earth who never sinned, Jesus. It may take awhile to see the results of sin, but if any of the 10 commandments are broken the end result is always death. Sin is a very bad thing (and not just because God said so).
Let's look at an example. Let's say that "using God's name in vain" is the law that gets broken. Seems like such a little thing, but when we use God's name lightly we are really setting ourselves above God. We are saying that we do not need Him and that we do not need anything that He could possibly give us (even though all good things come from Him). So are we saying that we can live without the sun, the rain, the plants that provide our food, or even without the air we have been given to breath? Of course we wouldn't have a chance, we would be dead in seconds, but you get the idea.
Here's another example. The commandment that tells us we must honor our father and our mother seems like such a little thing too, yet if we fail to bring honor to our parents it is because we are failing to be good to ourselves (we are not letting ourselves be really happy). Again, God wants us to be happy. If we don't care about our parents then we will not be truly happy. A lack of happiness in a life leads to depression and eventually it will lead to self-murder in one form or another. In other words, it will eventually lead to death.
So, does God hate sin because it makes Him look bad, or does He hate sin because of what it does to the one who sins?
The answer, of course, is that Jesus hates sin because it kills those He loves! And He loves us so much that He was willing to die so that we can live and be happy. Jesus took sin's end result, death, for us. This was the only way that sin could be eradicated from His entire universe and protect all those who trust Him! So put your trust in Him and don't sin anymore. (Remember that without Jesus we cannot do anything. So we cannot just quit sinning on our own, but He promised us that with His help we can do anything. So ask Him to eradicate sin from your life and then let Him do it. And don't resist when He tries to make those changes either.)
"As Moses lifted up the serpent in the wilderness, even so must the Son of man be lifted up."