The Ignatius Insight blog has had a lot of good stuff lately. Most recently it is an interview with Mark Brumley on differences between Catholicism and Protestantism. It points out that there are real differences in the theories of justification, but that is not the biggest barrier. The biggest differences are the Papacy, Mary, and efficacy of the Sacraments.
Of course, these sorts of differences are fairly minor - on the order of differences between Protestant denominations. For example, Presbyterians and Baptists disagree about infant baptism. Similarly, there are arguments about "real presence" in the Eucharist.
It reminds me that it is not our theology which saves us. We must have enough theology to have the right Jesus (without the right Jesus, you do not have the Father). But we must agree on the major and overlook the minor.