The thing that I am most proud (actually humbled) to have passed on to our kids is that all three of them get the heart behind my oft-repeated phrase that to have good friends you must be a good friend. I’m not saying I have always been the best friend. I’m definitely not saying I know everything about being a good friend. This is not a how-to post. You will have to read your own personality into this. These are just some of the things I have done (and am doing) to have friends that include those who don’t share my understanding of faith.
It should be noted that I did not have a step-by-step plan in fostering these kinds of friendships. In fact, my opinion is that doing it that way would seem artificial and wooden, and would likely be evident (and a turn-off) to the person you are trying to befriend. So this list was formed after the fact. I just looked back at the progression of my newer friendships and analyzed the commonalities. Among them are these…
Natural connections. In most cases my new friends came through natural connections (business contacts, parents of our kid’s friends, neighbors). Admittedly there were a few times when there were less-than-natural initial connections (i.e. one of my good friends and I met first through Twitter), but I think he would say that it was our connection when we met face to face that allowed for us to become “real friends”.
Not initiating religious discussion. I know I’m sure to get some pushback on this one… and that’s ok. I’m not saying that the Bible says to do it this way. I’m not even saying that this is the best or only way to connect. Here is why I chose to do it this way. Especially in my case as a pastor, once they knew that about me (usually early on, if not immediately), there were nearly-unscalable walls erected. The only way I knew to climb those walls was to disarm the preconception that I was just being friendly so I could preach to/at them. Let me make it equally clear that in every case, to varying degrees, that kind of discussion (religious) did come up sooner than later. I think most, if not all of my friends would say that this component was a huge piece in gaining trust.
The long haul. There is simply no substitute for time. Earlier I alluded to the fact that often Christians flee these kinds of friendships because the friend doesn’t convert to their way of thinking. Here is a simple (simply confusing) fact: I am friends with my friends for no other reason than they are my friends. Do I wish for each of them to know Jesus in the way that I do? Certainly. Will I stop being friends with them at any point because they don’t? No!
In conclusion, there is no purer reflection of God’s love than to work in this direction. After all, isn’t this exactly the way he has interacted with each of us? Romans 5 says it in the strongest way possible… He sent Jesus “while we were still sinners… while we were still his enemies” (Romans 5:8, 10).
re:THINK 
I have to say, following this thread of thought with you has been fascinating, Rob. As I’ve said to you many times before, I wish more Christians thought this way. I think it’s frequently forgotten that you have to be a person and a friend before you are a (fill in your religious belief or lack thereof here).