Life is a preparation for eternity/QUOTE]
you say: Life is a preparation for eternity. I would say, it’s rather than that, a probation for the worthiness to get to heaven.
Never mind

As I said before in several Catholic forums (earning harsh disapproval) - I never had a Catechism (accept when I was a small child when we in 1947 in school we had to have one; - I was 7 then and had an old used one, as we where to poor to buy a new one).
Most of our Holies didn’t have one, but they understood without. More believing people than not, don’t have one and live in God all the same.
The world however has to have “a Catechism” which is the teaching of the church, which was founded for that teaching by Jesus Christ.
I - when I was young man of about 40, I met an old lady who hardly ever had red a book and she was unable to speak fluent language and express herself properly. She not only believed in God, but she lived in God as a matter of course, as many of the Holies did. I at that time as today, considered her as a holy person and she lives in Gods kingdom today.
It was hr however, who taught me: When you pray, pray in the name of the Father, the Son and the Holy Spirit, then you REALLY prayed and God will hear you.
“Self studies” - ok - all right. But actually, believe in God and understanding, (as far as we allowed to understand) is hardly a matter of studies. It’s a far more so a matter of WANTING TO UNDERSTAND. If we really want to understand, understanding is given to us, no matter if we are intellectuals or never saw a school in our life.