I just read the
comment from your fellow Administrator (for_his_glory) and wonder whether I'll be wasting my time discussing Catholic doctrine here. All Catholic doctrine is completely in agreement with Scripture, although not all doctrine is spelled out so as to convince even the unbelieving Thomases of today. I am willing to try discussing with any noble-minded Bereans, I just don't see the sense in throwing pearls to any closed-minded Thessalonians. I've been there and done that, and it's a complete waste of time. And I've already met a few of these Thessalonians on this forum.
In the same comment from your fellow Administrator, we already see a great handicap that most people here will start off with, the mother of all "traditions of men",
Sola Scriptura. The idea that "everything we ought to believe must be spelled out in Scripture" is itself an unscriptural tradition that was invented in the 16th century. Not only is this doctrine not found in Scripture, it is explicitly refuted by Scripture.
Catholics on the other hand believe our
Rule of Faith is the Magisterium of the Church that Christ founded upon Peter. All the doctrines taught by Our Lord and His Apostles were initially handed down orally, and only later on were some of them written down, not in the form of a Catechism where everything is clearly spelled out and indexed, but rather as a collection of individual books and letters. And as St. Peter warned us, these Scriptures are hard to understand and easy to twist unto our own destruction. Hence, we read in 1 Timothy 3:15 that "the Church is the Pillar and Foundation of the Truth", not Scripture. This does not mean that the Church can contradict Scripture, as some like to gratuitously claim, but rather that the Church is the guardian of Scripture, making sure that Scripture is faithfully preserved and interpreted.
The fact that we start off with two completely different
Rules of Faith will make any discussion difficult, and will certainly allow the unbelievers plenty of room to "blaspheme whatever things they know not" (Jude 1:10). On top of that, most people on this forum have allowed Luther to rip quite a few pages out of their Bible, which complicates things even further.
So, I believe the best place to start would be to discuss our
Rule of Faith, rather than to work with two different standards to try and come to the same measurement.