It's true that we need to help lead people into the kingdom of God but once we get them into church..the ball goes back into their court again, meaning that it's their decision to take the next step to accept the Savior who has already come!
All we can do is follow where God leads us and listen to the voice of God that he would give us the opportunities to witness to people!
Don't be worried or ashamed when you speak to someone and they turn you and your message of Christ away, you were obedient to God's leading and God will send someone else to witness to them eventually!
God knows what he's doing and God works in mysterious ways that we cannot understand or explain at times but that's who God is and the way that he works, it's not our job to understand, however it is our job to obey him and we need to place everything we are and will become in his hands to use us for his glory!
Relax and take it easy, knowing that you did what God told you to do and trust that somehow that person will find salvation through Jesus Christ! It all starts with a seed that is sown and think about it this way..when we plant a seed and others come along and water it..what happens? It grows! That's what happens when we are obedient to God by witnessing to someone and then later on, more people witness to them until that person gets to the point where they must put their roots someplace! They become aware that they do need Jesus to save them!
So trust in Jesus and have confidence in him, that God will watch over that person and they will be reached!