Why Christians can't respect other's opinion?

[Vincent]

I've met plenty of decent Christians who respect my beliefs. I've even been friends with multiple theists (at the time I graduated high school I was the only atheist in my group of friends). I tell them I don't believe in God. They say "oh okay" and the topic is rarely broached again. 

So respectful people are out there! Unfortunately though, there are individuals who spoil the bunch. Many individuals, actually. When I told my cousin and his friends that I was atheist, they looked at me like I had just said I murdered Jesus, and proceeded to gain up on me. When I told my sister, she was devastated and said that I had "hardened my heart" or some silly shit like that. My coworker told me that God would send me to hell on the Day of Judgment. 

But the thing is, Christians such as those don't understand that they're being annoying. Because the way they see it, we've damned ourselves to hell. And they think that "warning" us or trying to convince us otherwise without evidence will save us. They see it as their noble Christian duty to "help us toward salvation". That's why they'll preach to you and bother you with their beliefs. 

Or that's my view of their actions, anyhow.