Back in 1981 I had a conversation with a fellow student at the University of Pittsburgh whom I'd met at an evangelical campus fellowship and who came across as mature, spiritually committed and Biblically literate. He also said during that conversation that he would never leave the Roman Catholic Church, something that confused and surprised me, who grew up in a conservative Reformed church which didn't believe that Catholics could be real Christians.
Two years later I was invited to attend a meeting of the Greater Pittsburgh Charismatic Conference, which was taking place at Duquesne University, and a priest delivered a Biblically accurate homily. I was scratching my head at that — a Catholic priest? And at a Catholic university? (I later learned, however, that the charismatic movement in mainline denominations started on a retreat of DU students in 1967.)
Since that time — and I beg your forbearance for sounding arrogant or patronizing — I've become a bit more charitable toward Catholics, understanding that God has His people there as well.
During Pope Francis' visit to the United States over the weekend I noticed a number of people blasting the church as inherently unbiblical, but I had no use for those statements. I've come to appreciate its social teaching, which I hadn't even realized until about two decades ago pretty much mirrors mine — concerned with stewardship of the earth, consistently pro-life (that is, womb-to-tomb) but also opposed to same-gender matrimony. In that the pope could claim correctly that he wasn't a political liberal, at least by American standards.
I do have theological problems with Catholicism, too many to mention in this entry, and many of my friends who grew up there have left the church. But I'm reminded of something that Charles Spurgeon said about John Wesley, with whom he had serious, and perhaps irredeemable, disagreements: When one person asked him, "Will we see John Wesley in heaven?", Spurgeon responded, "I fear not" — in the context that Wesley's passion for and commitment to God far exceeded their own. In addition, theology is generally a man-made construct anyway and can be a substitute for knowing God personally.
Thus, far be it from me to assume just how God will work as well as the vessels that He uses to do it.