Actually, you can have both, Scripture as the final arbiter of Truth, and the traditions of the Church. The Nicene Creed was developed to explain questions not explicitly answered in the Bible, BUT the debate centered around whether the offered answers were in agreement with the texts of the New Testament, and the Hebrew Scriptures. Thus, already, the Bible was considered to be the final authority, which would determine whether one answer or another was valid. The New Testament Scriptures were at the time considered to be the authoritative compendium of the Apostolic deposit, since the Council was convened 200 years after the last person who knew any Apostles had died. As on record, St. Athenasius of Alexandria possessed and recognized the authority of the complete canon as we know it. Therefore, the Nicene Creed is a reflection of the Scriptures, and does not stand alone or in contra-distinction from them.
There are three reasons why, today, I can't consider the Catholic Church to be sufficient authority for belief. This is their standard argument for trusting the Magisterium:
1. It's a mystery, so you're not supposed to understand it.
2. The Bible is not sufficient for an understanding of dogma.
3. The way we pray shapes the way we believe.
These "caveats" are where the Catholic Church spins off into grievous heresy. Such presumptuous arrogance, to assert that they should tell us what and how to believe, allows them to add accretions at will. Yet, they still want us to submit to the Pope's authority without question.
For example:
There is NO EVIDENCE in the Bible for the bodily Assumption of Mary into Heaven. There wasn't even any evidence of belief in such a story until after the Council of Nicea in 325 AD. Yes, you could say it's early enough to be included among the ideas held by some Church Fathers, but Arius was also early, and the Monophysites. Arius was a heretic, while the Monophysites caused a schism in the Church. The Assumption is not severe enough to break Church theology, but it is an accretion. There is NO evidence that any of the Apostles taught this. It's not even mentioned by John, who cared for her like his own mother. The story evolved much too late. Plus, it wasn't even required for belief until about 200 years ago.
The Catholic Church has a habit of condoning popular traditions and making them dogmas later. Just look at "Our Lady of Guadelupe." That's a heresy, on a par with Mormonism, not just an accretion. And then, Pope Francis is trying to appease world opinion with his "ecumenical" statements, trying to fit the Gospel into a rainbow of world religions. This can't be anything but heresy.
Jesus is uniquely Divine! Confucius, Lao Tsu, and the Buddha did not claim divinity. Nor did Moses or Muhammad. The gods of Hinduism are merely elevations of nature and philosophical conjecture into objects of worship. Meaning no disrespect to the people who practice these religions, but they have been deceived by their teachers. None of them lead to the Christ, the Son of God, who performed real miracles, taught true ethics and worship, sacrificed Himself so that our failures could be forgiven, and then RESURRECTED HIMSELF from the grave! Only the True God who created the Cosmos could actually do that. The amazing part is that He would choose to become a human being, and do that in history for us! All we have to do is repent of our pride and disobedience and believe in Him, and He promises us an everlasting life of joy with Him in Heaven! Do any of your prophets have the power to do that? No, they don't.
Inevitably, there comes a time when you have to trust your own reason, based on the roots of tradition, and stand on the evidence of how it all began. The Apostles had plenty of evidence for believing in Jesus. They had been his disciples for three years, living daily in his presence. They saw his miracles first hand, and listened to Him explain how his words and works fit into the old tradition. They knew beyond any doubt that He was their God, having seen Him in his glorified resurrection body on many occasions, often in large groups of witnesses. The Epistles and the Gospels were written early enough to be verified. There were witnesses still alive to be asked to corroborate the story. Thus, the Apostolic letters and documented stories must be held as foundational, from the time they were written forward. As Holy Scripture, they are the indisputable arbiters for whether our belief fits with the Truth about who Jesus was and what He taught.
At this point, we must be willing to admit to being less sure than we want to be, putting our faith and trust in our own meeting with Jesus in our hearts, as guided by the Bible. Any act of faith inevitably demands that we trust enough to stand humbly before the authority of God Himself. Any other claim to Truth must be regarded as tentative at best.
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