You can try your best to show an example. You can attempt to persuasively present the gospel, but often it falls on deaf ears. This is where John 16:8-11. Jesus reminds us that we don't have to rely on our own debating skills. He is sending the Holy Spirit to work in people's lives and minds.
Listen to Jesus' words: "When he comes, he will convict the world of guilt in regard to sin and righteousness and judgement: in regard to sin, because men do not believe in me; in regard to righteousness, because I am going to the Father, where you can see me no longer; and in regard to judgment, because the prince of this world now stands condemned." (NIV)
It is the work of the Spirit to bring people to the place where they see their need for forgiveness and to receive his righteousness. May I suggest that we look to see where the Spirit is working in people's lives? Then relying on the Holy Spirit let's seek to minister.