It is not up you to lead a person to Christ. It is the Holy Spirit who convicts. Often times Christians are well meaning, but they do more damage than good. They think that they have to convince them and that if they don't do it that person is damned. It sounds like your friend has heard lots of the kind of talk which shows little of God's love and grace.We play a big role, but we need to be good listeners and then we will know where to start. A good model for evangelism is in Acts 17 where Paul is confronted with the Athenians and their intellectual pride and idolatry, certainly a hard crowd to convince. He begins with something familiar to the Athenians, a statue to an unknown god, then he tells about God and stops when he knows that he has said enough. He has planted a seed that may grow in time. He isn't ready to plant and harvest all at once.It sounds like your friend has some wounds from previous contact with Christians. I would listen to him on this. I would not focus on either the idea of being inclusive of other faiths or exclusive. I would say that all religions have something to offer to their followers and so does Christianity. This neither advocates other religions or "pushes" ours.I would share with him what makes Christianity unique. It is the only religion based on relationship. Many religions are based on following rules (e.g. Judaism and Islam) or self-centered, emphasizing drawing inward to reach a higher state of personal consciousness or being (Buddhism or Hinduism). Christianity is based on having a personal relationship with Jesus and at the same time serving others, by putting their interest ahead of our own. It is based on the idea that God created us out of love in order to have a relationship with him. There will be problems along the way in witnessing, but go slowly. Inevitably the idea of suffering comes up. How can a God of love allow suffering? Be prepared for this. Remember that God did not create suffering, he created the world perfect, but he did give us free will and this is where suffering begins. You can't have both free will and no suffering, unless we are prepared to always do it God's way which is what this life is all about, to teach us that we can freely choose to follow God and do it his way or suffer the consequences. In the end pain and suffering is transient, as God has promised to create a new world, free from pain and suffering. For now we are like children, feeling our way and getting hurt. It is part of the learning curve. Good parents have to let their baby take its first steps and stand back knowing that the child will take a few bruises along the way. The parent is hurt when the child falls, but he is there to dust off the child and dry the tears. It is the same with God. He loves us that much that he allows us to grow and learn, becoming independent, creative and intelligent beings. He longs for a relationship with us in which we come to him of our own free will. When we freely give back the love to God that he has for us then he rejoices because we are made in his image, to love and be loved.You cannot convince anyone who does not want to hear. Know when to back off. In your own devotions, you need to pray lots for that person and to pray for wisdom and discernment for you when talking to him. Be honest. If you don't know an answer don't try to bluff. Many Christians make this mistake, especially in the area of science with someone coming from a scientific empirical background. We say some dumb things that they can easily refute and then we have lost our credibility before we start.BTW, this is my first post here, too.Blessings,Dunamite