Possible, yes. Just like its possible to believe in Islam, Joseph Smith and Watchtower. The problem is, all of these are based on the Bible. But each one, including praying with/to the dead 'saints' (you say with but the catechism says to), are all man-made additions to the Bible.
If the Bible was so wrong that man had to amend it, and change it, then what does that say about the root belief?
I can go all throughout this season, believing the Cardinals will win each and every game. I can even believe it is Cardinal Red in the Super Bowl. But the powers that be say otherwise. The powers that be, will beat the poor Cards most of the time, this season. What I believe has nothing to do with it.