You don't have a clue how many are. And in fact since most people believe in the same god you do it only makes sense that most pedophiles say they believe in your god too
prisons of full of religious people you know.
I don't know if it was intentional, but ^that^ was very deceptive and misleading.
First of all, there's a huge difference between "believing" in the sense of merely believing in the existence of God.... and believing in the sense of being saved, which is not about mere belief, but faith, trust, loving and actually following God. It means being born again - spiritual birth, which literally makes one a new creation.
The overwhelming majority of the world believes in God or a higher power. But much fewer people are in the latter category. Jesus said "enter through the narrow gate.... the way is narrow that leads to life, and few are those who find it."
Obviously criminals are not following Jesus. However, since prison ministry is a thing (by prison ministry I mean Christians who visit prisons and share the Gospel with prisoners with the intent to reach them for Jesus) some prisoners actually DO come to Christ while in prison... but that's after they did whatever got them there. There might be others who lie about believing in God, for their own selfish purposes, maybe to get out early, I don't know.
So anyone can say anything, that doesn't make it true. If you're not sure about someone who claims to be a believer, here is what Jesus had to say:
"You will know them by their fruits. Grapes are not gathered from thorn bushes, nor figs from thistles, are they? So every good tree bears good fruit, but the bad tree bears bad fruit. A good tree cannot bear bad fruit, nor can a bad tree bear good fruit." - Matthew 7:16-18