Is it okay to hate that my best friend is a Christian?
Why do you have a problem with your best friend being a Christian?
I hate that religion. I also hate to see people being unhappy by their own fault
You should practice accepting your friend for who he/she is and respect his/her values. Discriminating against any religion is unacceptable. Instead, talk to your friend so you can understand his/her religion better.
Christians are losers.
Religious persecution is a thing of the past. Accept your friend and anyone's religion, as that is their personal right to do so. You would want other's to respect your beliefs, so return the favor to your friend.