It is important to note that knowledge of doctrine is not salvific in itself; doctrine, in all its artificial manipulations, is a fundamental part of learning more in the faith, but that presupposes that you had faith to begin with. The Catholic Church is just as legitimate a foundation for initiating faith as Sunday School for evangelicals. The point is, doctrine is supplementary not a necessity, and in itself, not worthy of saving. It is the "knowing" of Jesus Christ that has the power to save, the relationship formed with him. The "basic" doctrine we integrate essentially with the personhood of Jesus Christ, such as His resurrection and authority, but doctrines about transubstantiation, virgin mary, saints, etc. seem much like a benign tumor in my eyes that might hinder faith, but has no part in obstructing it completely.

So, the Catholic Church is legitimate in its approach to God, but definitely not the only one.