In my study of Catholicism, I've come to a realization. Having traced many of the innumerable differences in the schism between Protestants and Catholics, I believe there is one that defines the schism at its core, in its totality. Every other difference are traced to this root. I believe the difference is this: Protestants emphasize soteriology, and Catholics emphasize ecclesiology.
What do I mean? Soteriology means "the doctrine of salvation." Protestants fixate on the event of salvation, the moment of conversion, when one comes to know Christ Jesus as Savior and Lord. Our faith is personal, our culture individualistic. We typically disdain church authority, because it might interfere with our connection with Christ. We shy away from Mary because we fear the honor we give her might eclipse the glory we ought to give to God. We do not call upon the saints because we have Jesus as our one mediator before God.
The Catholic response, in contrast, is much less atomistic. I do not mean less individualistic, for individualism (as with most of Western culture) is drawn from Catholic tradition. But while Catholicism does emphasize the dignity and worth of the individual, this is only the foundation, when Catholics would prefer to admire the cathedral built on top of it.
Ecclesiology means "the doctrine of the Church." It is in the Church that the Catholic lives and breaths. Catholics focus on the experience of salvation, the context of conversion, when one comes to live with Christ Jesus as Father and Redeemer. The faith and the culture are not tied up in an individual's relation to God, but in the relation of God to His family, and thereby to each member of the family.
Throughout the New Testament, Christ is referred to as "the firstborn" (Heb. 1:6), "the firstborn of the dead" (Rev. 1:5), "the firstborn of all creation" (Colossians 1:15), and perhaps most significantly "the firstborn among many brethren" (Romans 8:29). This is one of the titles of the Christ, hearkening at a deep-seated reality: that, as a result of the Cross and the Resurrection, we have been joined to Christ and can call ourselves true sons of God. In Galatians 3:26-29, Paul tells us that "you are all sons of God through faith in Christ Jesus, for all of you who were baptized into Christ have clothed yourself with Christ.... And if you belong to Christ, then you are Abraham's descendants, heirs according to the promise."
This doctrine is one of the essential truths of the faith, retained by Catholics though in my experience forgotten by many Protestants. Salvation is bigger than forgiveness: it is our familial relation to God. We do not address God as "Our Father" simply because He's humble enough to listen. It's a statement of fact, a new reality that by the power of Christ He really is our Father. He descended, to raise us with Him.
Over the next few notes, I'll be exploring a few other Catholic images for the Church. However, this doctrine of divine filiation, and this understanding of the Family of God, is foundational to all the others, and indeed is one of the cornerstones of Catholic teaching.