The greatest single cause of atheism
in the world today is Christians,
who acknowledge Jesus with their lips and walk out the door,
and deny Him by their lifestyle.
I personally believe that the best way to bring people to God is to show the love that God wants us to - the love that Jesus taught. I'm not saying to go all mushy on them, but who God wants you to be.
If you were like this, it would draw more people to God than handing out a pamphlet.
That is what an unbelieving world simply finds unbelievable.