Leithart’s excellent article is making its way around the internet. The most salient part of his piece is this:
I agree with the standard Protestant objections to Catholicism and Orthodoxy: Certain Catholic teachings and practices obscure the free grace of God in Jesus Christ; prayers through Mary and the saints are not encouraged or permitted by Scripture, and they distract from the one Mediator, Jesus; I do not accept the Papal claims of Vatican I; I believe iconodules violate the second commandment by engaging in liturgical idolatry; venerating the Host is also liturgical idolatry; in both Catholicism and Orthodoxy, tradition muzzles the word of God. I’m encouraged by many of the developments in Catholicism before and since Vatican II, but Vatican II created issues of its own (cf. the treatment of Islam in Lumen Gentium).
I agree with those objections, but those are not the primary driving reasons that keep me Protestant. I have strong objections to some brands of Protestantism, after all. My Protestantism – better, reformed catholicity – is not fundamentally anti-. It’s pro-, pro-church, pro-ecumenism, pro-unity, pro-One Body of the One Lord. It’s not that I’m too anti-Catholic to be Catholic. I’m too catholic to be Catholic.