I strongly agree with your statement. Many of my classmates don't like to speak with me, or even "look down" on me for my un-Christian views. In addition, I've had multiple girls refuse to date me simply because I'm not Christian. Although one could argue that the girls are using that as an excuse to just not date me, I'm talking about the cases when I've become very close to the girl, and the next logical step would be to date.
Whatever the case may be, I certainly have heard people at least claim that they don't want to spend time/go out/talk with me because I'm not Christian. People think it's wrong to discriminate based on race, but when discrimination occurs based on religion (on a small scale, I'm not talking about the holocaust), it's suddenly justified because that's part of the religious doctrine?
I used to be Christian, and at my church, we were told as kids to only have close friends with people within the church. Having friends with anyone else would supposedly cause us to turn away from the "truth" and fall into temptation.
No amount of careful planning will ever replace dumb luck.