So what is the main thing anyhow?
The easy and obvious answer is Jesus. That's a true enough answer; indeed, the likelihood is that in the end he will pull all our chestnuts out of the fire--redeeming a flock that was often lost and roaming frequently, that rarely saw the forest for the trees, and that made a shamble of just about everything he entrusted to them. Though Christians may be in a truly sad state, Christians' joy is in their good shepherd who cannot fail. Jesus is the main thing.
In a heirarchy of importance from there, what would come next? I say it is the Holy Spirit. The Holy Spirit is what makes the things of God known to us, what convicts and draws us. The Holy Spirit is what births us in Christ. The Holy Spirit is he who guides us and leads us since Christ ascended. The Holy Spirit is our means of walking with God and truly doing his bidding. Apart from the Spirit we're aimless sinners.
After Christ and the Holy Spirit I would say the Bible comes next. Though we are people of the Book, Christianity is not primarily about facts and figures, equations and hypotheses, structures and forms. Christianity, at its heart, is experiential--about a living fellowship with God through his indwelling and empowering Spirit. Confessions, theology and theologians, generally, only cloud the issue. The Bible in and of itself is all that is doctrinally dependable, and that not so much in that it gives us the necessary body of knowledge to know, but in that it objectively tells us how to live in the Spirit by faith.
After these nothing else is really important of itself, for the first three encompass anything else that could be of import.