Aren't Christians supposed to be loving?

Just asking this because I see many Christians on this site having a go at atheists. I acknowledge that this is not all Christians. I understand that atheists have rants about Christians and in response Christians have rants at atheists. But doesn't the Bible teach that you shouldn't go out seeking revenge? Or so some claim, I'm not sure. I often see many Christians on this site who aren't being loving towards people who have different beliefs.