I've been a little cagey on this blog about anything that might actually deconvert anyone. Losing your faith is hard, and until you're actually in that situation, you might not be aware of how many parts of your life would be affected.
But it occurs to me that I shouldn't be taking that burden on myself. After all, it isn't my job to make sure you stay Catholic. It's yours. And I have to warn you: if the most important thing in your life is to stay Catholic, you can't be too careful. There are dangers everywhere. I ought to know.
For instance, it's well known that comparative religion courses destroy people's faith. It can be a big blow to find out that other people believe things you know are wrong, but feel just as sure about them as you do. You find yourself wondering how you can be sure yours are right and theirs are wrong. So don't study other religions, except apologetics books that show you how to respond to them.
Going to college at all correlates with loss of faith too. There's a lot of discussion about why that is, but to be safe, you'd probably better not go to college if you haven't already.
Even using the internet correlates with loss of faith. So maybe you shouldn't just give up this blog, but all blogs. It's possible that by carefully clicking on Catholic links only, you can stay safe, but I should warn you that I did try this and it didn't work for me.
We all know having a non-religious parent makes you more likely to disbelieve. Of course you can't help that, but you can do your best to pick a spouse who believes exactly what you do and hope they won't change their mind. That will give your kids a fair shot at keeping their faith.
It's much easier to believe when all your friends do, too. Harness that positive peer pressure and drop your unbelieving friends. They might give you the impression that unbelievers can be as virtuous or more than Christians, or mention an argument you can't answer.
Don't be methodical about the way you think, at least not in a scientific, empirical sort of way. If you get in the habit of expecting your beliefs to come from evidence, of changing your mind when you learn new information, of listening carefully to the cognitive biases that may be affecting the way you think, you might start expecting your religion to meet the same standard.
If you have kids, you should probably make sure to be very strict and harsh with them. If you breastfeed them, like I did, you won't be able to spank them because you're too attached, and that will drive you to read liberal namby-pamby parenting books and websites. Do that, and you'll realize kindness and freedom work so much better than threats and punishments. And once you've come to that conclusion, you'll find yourself asking, What the heck was God doing throughout the whole Old Testament?
Don't buy into secular notions like liberty, religious freedom, or equality. You'll notice that the Church hasn't always been fans of any of them, and in fact it's arguable that it's still a bit suspicious of these ideas. To be a Catholic without doubts, you're going to have to accept that slavery and forced conversion are, at the very least, not a huge deal.
Don't study history, at least not thoroughly. If you do, you'll learn the level of independent historical attestation that's necessary to confirm past events, and you'll find that the Gospel accounts fall quite short of this. You can still choose to believe, but it will be made more difficult.
Pray, of course. It will help. But don't get too serious about your faith either, because if you take it really seriously, you'll realize that there is no excuse for spending any of your time and energy on worldly things when eternity hangs in the balance. You'll start nitpicking ever smaller and smaller things you do, and the motivations behind what you do, and develop scrupulosity -- a disease no one outside of religion ever gets. That will encourage you to abandon your faith because you can't be "balanced" about something that matters this much.
Don't read the bible too much, at least not without a guide to help you. God's inerrant word is very dangerous and hard to understand. It might be best not to read theological books either, because some church teachings look like the opposites of other ones.
If something seems contradictory, don't admit that, even to yourself. Say that you are too stupid and uneducated to understand it, and seek out someone to explain it to you. Don't google it or you might get the wrong kind of answers.
And whatever you do, never read anything that amounts to anti-apologetics. Read The Case for Christ, and don't ever google "answers to The Case for Christ." Read Peter Kreeft and no Richard Dawkins. That sort of thing. Never click on anything with the word "atheist" in the title. Some people say it's a sin, and anyway, do you want to take the chance it might convince you?
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However: if your main goal is to believe what is true and do what is right, rather than to remain in the religion you are currently in no matter what -- if the reason you stay Catholic is because you think it is good and true -- then you don't need to worry about any of the above. If the Catholic faith is true, it can handle exposure to any new information or argument. As people used to tell me, the Truth is a lion, it doesn't need to be defended. You don't have to try to believe what is apparent.
Sure, if you make seeking the truth your first value, above staying Catholic, you run the risk that in the case they conflict, you'll have to leave the faith you love and find fulfillment in. That will break your heart. But that's only true if the Church is wrong. If you're sure it's right, you don't have to be afraid. You could read all the stuff that I've read, which made me think the things I currently think, and then keep searching till you've satisfied yourself that I am wrong. The information has to be out there.
The question you should answer, right now, is this: if the Church were wrong, would you want to know? If the answer is no, you can't be too careful.