1. Getting baptized basically makes you a Christian for life. Your parents do your promise instead of you yourself so basically you are not given a choice to not be Christian if your parents say so. It's a self-serving ritual and becomes meaningless if you don't believe in it. I disagree with this as everybody should be able to make their choice and be able to change it at any time. Christianity does not allow you to leave technically. But only as long as you believe in it. If you don't believe in Jesus, it makes the ritual meaningless since its whole purpose is based on believing that it has one.
2. No sex before marriage; I completely disagree. I understand that there should be a way to force people to look after their children who aren't careful with sex. But marriage comes down to one thing again: Make a promise and being forced to keep it. In Christianity it's literally "until death parts us" so sex is basically prohibited before marriage to make sure you do your parental duties in at least some way. It's not a bad thing, but with today's laws about child support and protection during sex, it becomes obsolete.
3. The Jewish god is vengeful and killed millions of people in the Old Testament. The Christian god will forgive you even if you destroyed the entire universe as long as you're just honestly sorry about it. I can't believe in a god that will erase all consequences of your actions, it doesn't seem right. Don't get me wrong, forgiveness is a good thing, but there has to be a limit. If somebody does the same mistake over and over, there is no point in forgiving them as they aren't making an actual effort to not make that mistake anymore. Which means that they obviously aren't sorry.
4. Honestly, I forgot what #4 was. xD
These may seem like "minor" stuff, but they are important to Christians.