He pointed out how secularists have faith as well. He has two questions for people who claim they have no faith: How do you know there's a world outside your head? How do you know your memory is reliable? Encourage them to answer these questions without faith as the basis of their answer.
He's now singing us "The World View Song." "Every world view is based on a commitment of faith." When agnostics ask for proof they want a demonstration. The thing is that demonstrations only give answers to small questions.
There is a way to prove Christianity is true: Without it we sink.
Without a Christian faith commitment the following questions are hard to answer:
How are there absolutes in physics?
Why are there moral absolutes?
Universals can't be based on the limited. Prov 1:7 says the fear of the Lord is the beginning of wisdom. Starting with humanism fails. Beginning with God you can prove everything.
Christianity has no problem aswering the big questions because it begins with God and not man.