All Christians are de-facto family. We’re children of God, that makes us siblings. That might not make you totally thrilled, the thought that you are going to spend eternity with me… but it is as it is. I’m sure it will be more fun after God gets through perfecting us. 😉
Family is where you let your hair down. You can squabble a bit, or argue about the really most awesome place to put the TV remote… but you’ve got each others’ backs. You’re family!
So it is with us Christians. I might argue with one of my sibs over some point of doctrine for our mutual edification – iron sharpens iron and all that – but we understand that we’re both under God’s authority. It places a limit on our quarrels. (Mostly. It should, anyway).
What should family do for one another? Well, we should support each other, love each other, encourage each other, build each other up.
But non-Christians aren’t family, so we need to be on best behavior around them. Our job is not to sharpen them, it is to show the glory of God our Father and introduce them so maybe they can join the family.
Different groups, different jobs.
Just something to think about. Well, that and the bit where we’re stuck with each other for all eternity, so we should a) enjoy that and b) remember that when we interact one with another.