What about when people ask difficult questions like Why does God allow suffering? or Surely science has disproved Christianity? First, answer with gentleness and respect (1 Peter 3:15) and grace (Colossians 4:6). This means listening to people, asking questions, being patient and showing love. Less is often more so give people time to think about what you have said.
Second, answer by pointing people to Jesus. People often ask intellectual questions and we show respect by treating their questions seriously. But the Bible says that when people reject God the problem is not an intellectual one, but a moral one (Psalm 14:1). The problem is not that people do not know the truth; it is that they will not know the truth. They decide against the truth because they don’t want to face its consequences and submit to God (Romans 1:18-25). So don’t be afraid of intellectual arguments. Make it your aim to introduce people to Jesus Christ and his word. Try to answer their questions by directing them to Jesus – to some of the words he said or something he did. This means that they are not being confronted by something which they can dismiss as your point of view. They are being confronted by Jesus Christ – the person who is the truth.
We do not need to tell people the whole gospel every time we get the chance. This is because evangelism is not an event, but a lifestyle. It takes place in the context of an on-going relationship in which other opportunities will arise. We believe God is the great orchestrator of mission. So we look for opportunities to talk about Jesus, but we need not be overbearing when those opportunities arise.