Now as to tradition, it should not be discounted entirely, but it should not be some sort of sacred cow. Take, for example, the authority of the Pope. There is nothing all that conclusive in the Bible about that, though Catholics, of course, can quote scripture indicating that Peter was given the keys to the kingdom, etc. Whether or not this made him the vicar of Christ - that can be debated.
Or, even more difficult, at least for me, are some of the traditions that have grown up about Mary. The Bible doesn't even mention the names of her parents, but many churches are named after St. Anne, said to have been her mother. I don't presume that tradition in such instances does much harm, but I'm not sure that Christians should have to believe it.
More serious, I feel, is the absence of veneration of Mary among the earliest Christians. Take St. Paul. He wrote all those letters to the early churches, instructing them in doctrine, but never once mentions Mary. If she should be as central to the Christian faith as Catholicism claims, one would have assumed that he would at least made a couple references to her. Then, as to two of the main doctrines - the immaculate conception and the assumption - it was not until 1864 and 1950 respectively that these two dogmas were defined and made infallible by fiat of the Pope. Perhaps my main problem is believing that Mary lived a sinless life. Nothing in scripture suggests that, but the Bible does say that "all have sinned and fallen short....." That would seem to include Mary. The Bible calls her blessed, as it calls a couple other Biblical woman, but doesn't suggest that she was sinless. I prefer her to be a relatively normal human being myself rather than too much like a goddess.
As far as the gospels are concerned, Mary is mentioned only twice from the trip to Jerusalem until the crucifixion. Even as a child I was troubled that Mary and Joseph had gone a day's journey from Jerusalem before they realized that their 12-year-old son was missing! And in both references to Mary in between - Matt. 12:46-50 and John 2:4 - Jesus seems a bit dismissive of his mother. Sorry, but that's how those passages sounds to me. The other vague references quoted, as in Genesis and Revelation, hardly are very specific re Mary unless you already believe Mary is just below Jesus. In some churches she even seems to receive more attention than Christ - as, for example, in the Rosary. How many prayers to Mary compared to the "Our Father", taught by Christ himself?
That's all for now. Except to add that I have read the Church Fathers, and they were wise and learned men for their time, but so much of what they wrote is contradicted by what we have learned since - about the heavens, for example. Tradition is fine up to a point, but not when it keeps people believing the unbelievable.