A little reminder from one of the church fathers on our limitations:
When the idolatry and irreligion filled the world and the knowledge of God was hidden, whose part was it to teach the world about the Father? Man's, would you say? But men cannot run everywhere over the world, nor would their words carry sufficient weight if they did, nor would they be, unaided, a match for the evil spirits. Moreover, since even the best of men were confused and blinded by evil, how could they convert the souls and minds of others? You cannot put straight in others what is warped in yourself... Once more then, it was the Word of God, who sees all that is in man ... who alone could meet the needs of the situation. (Athanasius, On the Incarnation, §14)
Athanasius reminds us that it is only Christ, the Word of God, who can reveal the Father. It is Christ who must draw unto Himself. It is only Christ who can save.
That means its not up to us to convert people. All we can do is present Christ to them. We can't make anyone become a Christian. Our job is to take them to the person who can make them a Christian - Christ Himself. Evangelism is about presenting Christ to people, and He'll do the rest. Afterall, as Athanasius said, 'You cannot put straight in others what is warped in yourself.' But you can tell others about the one person who can.