So the first effect of Christianity is to make people stop and think. They are not simply overawed by some great occasion. They say, “No, I must face this. I must think.” That is the work of the Spirit. The people in Acts thought again. They repented—the Greek word is metanoia—they changed their mind completely. The Spirit always leads people to think, and, as I have been showing you, the greatest trouble is that men and women go through life without thinking. Or they think for a moment but find it painful, so they stop and turn to a bottle of whiskey or television or something else—anything to forget.
Is it not obvious that the world, speaking spiritually and intellectually, is in a doped condition? In all sorts of ways men and women evade the facts. They can do this with great energy, they can be very intellectual, but ultimately they end up with nothing.
What does the Spirit make us think about? Well, not first and foremost about ourselves. I must emphasize that Christianity does not start with us. It does not say, “Do you want to get rid of that sin that is getting you down? Do you want happiness? Do you want peace? Do you want guidance?” That is not Christianity. That, again, is the approach of the cults. No, these people in Jerusalem were made to think about Jesus Christ! They were given the objective, historical facts about this person. Peter had just said to them, “Therefore let all the house of Israel know assuredly, that God hath made that same Jesus, whom ye have crucified, both Lord and Christ.”
The next verse continues, “Now when they heard this”—they were not thinking about themselves but were beginning to think about Him. That is always the message of the Christian church. The true Christian message brings us face to face with the historical facts.

Martyn Lloyd-Jones, “Becoming a Christian,” in Authentic Christianity, 1st U.S. ed., vol. 1, Studies in the Book of Acts (Wheaton, IL: Crossway Books, 2000), 53–54.