John Piper is asked why he thinks Christianity is true. He gives two reasons and then a final one that he says is most “existentially real for me”.
The first is historical:
“I think arguments can be mounted that are solid and compelling first for the existence of Jesus and then for the death of Jesus and for the resurrection of Jesus to give an account for why the Apostles were the way they were after his death. So that the arguments that …evangelicals have developed for the resurrection of the dead “who moved the stone” type arguments, that’s the name of a book, are strong and have helped many people get over the barrier because if Jesus has been raised from the dead never to die again and ascended into heaven then we should take very seriously and credit what he said about himself.
The second is presuppositional:
…without God as an assumption, without the Bible as an assumption, all of our reasoning processes or all of our perceiving processes are not possible. In other words every time we start thinking and every time we start perceiving, something is happening in our heads which means something and if you’re going to have any kind of credible conversation about what you’re thinking or about what you’re seeing then you are assuming certain laws of logic, certain laws of causality, certain laws of existence, which can’t have any bearing or absolute significance unless they’re rooted in God. So everybody’s talking nonsense but hardly anybody will will say we’re all just animals talking nonsense
So here is his main one:
If someone said to me, ‘tell me in 30 seconds why you are a Christian’, I would say ‘The portrait that I see of Jesus Christ, in the gospels, is self authenticating to me. I cannot meet this man and have him speak like nobody else spoke and not believe him. He wins my trust.’
And then if they say ‘Ah but how do you know that person has not been created by somebody else.’ Then I would say ‘Well, then the person who is creating him is just as phenomenal and they win my trust. And if they win my trust then they are not lying to me.’
The Apostle Paul is not a lunatic. I cannot read the 13 letters of the Apostle Paul and think he is crazy or think he is a liar.