Light to the Light and Salt to the Salt?

Who ever turns on their high beams while driving at noon on a sunny day? Christians, well, figuratively speaking. I learnt from one of my Church's 
teaching pastors that within 2 years of being a Christian, most people have 
ONLY Christian friends. AKA, a little Jesus club of sorts. I know some people 
who would chime in and say: "I spend time with a lot of non-christians on a regular basis" aka.....they are viewed as projects; little corners of darkness 
in their otherwise shadowless world. They aren't really "friends", they are co-workers that are put up with, friends of friends that are avoided, ex-friends that are merely a stinging reminder of a life lived pre-Christianity. They are looked upon with sadness labelled "love" or "my heart goes out to them". It's as if we 
go around and advertise how salt of the earth, or light of the darkness we are without really showing it. It's like going into a home store to look for a lamp that is labelled: "Brightest lamp ever!" but you can't ever turn it on and experience it's warmth- there's no sample light out anywhere; you're intended 
to stand back and wish JUST WISH, you could somehow be as warm and lampy as that- and when you are...well.....as if you're own light isn't enough, THEN you get to experience theirs'. 


What is going on? Who said it was a good idea to be light to light and salt to salt? Why can't Christians be friends with non-christians? And not: "I'm only you're friend so I can lead you to Christ and feel like a better Christian" version of friend which is not genuine at all- but a true friend. You actually hang out, listen to their stories even if they heaven forbid-curse. It doesn't mean conform to a style of life you're not comfortable with, it means truly taking the chance to invest in someone that isn't a youth group leader, or former vbs go-er. A lot of people might disagree with me, and if they do I beg of them: show me the biblical evidence. There is nothing wrong with being a genuine friend to someone whose worldview differs from yours. Be blessed by a different perspective, and allow them to be blessed by yours. Keep your friends with common views close and lean on them when you need to- but don't succumb to the false ideaology that you and your friends are really a club- and only Christians are allowed.