I wrote a post some time back entitled this. I said that all Christians are called to be worldchangers and to witness for Christ.
Well, one of my brothers brought to my attention that not everyone is called to go talk to unsaved people who do not ask about our faith. Paul says, "have a ready answer for when people ask about the hope that is in you". When they ask, not when we see them.
Also, my mom pointed out that our brothers are not unbelievers, brothers are believers. So when the Bible says "when you see your brother overtaken in a fault, confront him", it's talking about your brother, spiritual brothers, those who believe in Jesus and follow Him.
I hope I didn't cause confusion. I was not clear on this point myself. Not everyone is called to actively change the world. All we are all called to do is be good witnesses, through the way we live. "So that men may see your good works and glorify your Father Who is in Heaven."
I apologize for putting the wrong idea out there. I hope I've cleared it up!