The problem is that Christianity has so many built-in defense mechanisms to protect the scams contained therein. It is the largest scam in the world--religion itself has most of the people caught in the scam.
First, you have such a heavy penalty for disbelieving. That alone prevents most rational people that are caught in the scam from looking outside. Hell and death threats are severe, plus there is the knowledge that anyone that is a heretic "has sinned against the Holy Spirit" and should not be paid attention to. That alone prevents Christians from looking objectively at their religion. Instead, they look within the religion for answers, and when they do not find answers, they use another mechanism to protect the scam.
Which is "Wait on God". When we don't have answers and cannot find them within the religion, the thing to do is to wait on God to reveal the answers. And they are kept waiting their whole lives, afraid of running ahead of God by looking at independent sources. This is similar to the mentality that perpetuated the First Dark Ages for a thousand years. Waiting on God instead of doing some science has kept many in the dark for their whole lives, and they are thus prevented from seeing through the scam by science and observations that clash with their beliefs.
Another part of the scam is the need to recruit others. This is why many Christians will bash atheists and those who promote atheism and/or Satanism. Everyone that is taught the fact that it is a scam is a poor prospect for falling for the scam. That is why it's so hard to get learned atheists and learned Devil worshipers to become Christian (as opposed to those who just dabble with it). Once you learn the scam, you will not believe their lies again. And they know it--so they attack anyone that exposes them while tuning out any messages that might teach them that they are in the world's most successful scam.
We also have prayers. Has anyone else noticed that God never answers prayers in a direct way? Even though the Bible has references to prayers that were answered in ways that are unmistakable. Don't believe me? Has anyone at the Kingdumb Hell ever prayed that God bring in everyone in the world within the next two hours before field circus? No, though it would have handily accomplished God's supposed purpose. It would also be blatant that God answered it, and God cannot have that. Or, that the world be set free of totalitarian governments that control whole countries and threaten to control the whole world? Or that all cancer be cured tonight? Notably, God never answers any prayers that are unambiguous. Rather, He will "give you the strength to endure" or someothing like that--which is impossible to prove that God did it.
Every religion has its defense mechanisms to prevent the average believer from seeing through it. Otherwise, they would lose their members and have a miserable time getting new ones. And, if that happens, they would all go belly up. The most successful religions are also the most difficult to see through--even though they contain the Original Sin lie, the "need" for a savior from same sin, and strings attached for that salvation. And the need to not pay attention to anyone that points out that their religion is a scam.