Some asked my this question. I thought it would be a good topic for discussion. Here is my relpy.
How do you know that the RCC is teaching the truth?
I have spent many years searching for the truth. When I first became a Christian, I was 15 years old. I had no faith background to speak of whatsoever. A friend of mine, named Paul (which I find ironic since I would consider myself a gentile up until that point) shared Jesus with me. All that Christ had done for me took me by surprise! I wanted to know this Person and let Him into my life. Well, to make along story even longer, I got into youth ministry after high school at my church (a bible church), and part of being involved in youth ministry was training. In one of these training classes we were asked what define our life goal. After thinking a bit, I put down, “to learn as much about God as humanly possible, without loosing the love and sincerity of the Gospel.”
At this point I would consider myself an Armenian theologically speaking, but this was soon to change. I worked at a Christian bookstore, and one day started talking to a coworker, who happened to be a Calvinist, (Anglican Calvinist to be more precise). We started talking and I would ask questions about what she believed. We would hang out outside of work and I ended up meeting her friends (all Calvinists) and we would get into discussions. Her arguments were very convincing and the books I read were as well (R.C. Sproul, Mike Horton).
I was a staunch Calvinist from that point on. To me, you (sandusky) would not be considered Calvinist enough, for you still hold onto a Baptist notion of baptism. I was also very anti-Catholic. I almost got into a fight with a friend (and bitten by his pit bull) because he thought Catholic were Christians! I had heard this from time to time in the circles I would run in, but I always came down on the side of a Sproul, or Mike Horton. To me they had corrupted the true Gospel with a bunch of man-made, unbiblical, and unnecessary material. The Reformation was the removal of all that was unbiblical and unnecessary, it put Christianity back on track.
But you know what? I hardly knew anything about Catholicism, aside from what I learned from Luther, Calvin, Sproul, Horton, and MacArthur. I thought that if I was ever going to make any headway with Catholics, and I mean real Catholics, like the ones on this board, I had to understand Catholicism better than they did. I had to be able put out the best arguments for it and systematically dismantle it before their eyes. I mean, how can you destroy something unless you know its strengths and weaknesses? I was going to find its weakness through knowledge. I started looking into Church history to see just where the Church started to go wrong. If I did this, I knew, I could convince any fair-minded Catholic their Church had erred. I started to read the Early Fathers and ever changed my major at school from History to Religious Studies. My University was unique in that it had (as a secular university) a Catholic Studies program. It was here that I could study not just with pop books, but also with real Church scholars. Through my studies I came to some harsh conclusions. I came to understand that my faith, my Protestant faith, was not present in the Early Church (aside from what is in agreement between Protestants and Catholics, i.e. the Trinity). The Early Church never believed in the solas, except sola gracia, which Catholics still believe.
With this new knowledge came a choice. To put aside what I had learned and abandon my search for truth, or follow the Truth wherever it lead me. And this is what I did.
Sorry this was so long.