I think Jim G. overstates the case. Protestants in general assume the RCC has apostatized on many theological matters–which was what the Reformation is about. Protestants don’t assume that the RCC is their only ally on public policy matters touching issues of faith and morals. If** nothing else Jim G. overlooks the Eastern Orthodox Catholics who if anything are even more steadfast than the RCC.** For much of the period immediately following the Vatican II Council, conservative Protestants were not certain at all that the Catholic Church wasn’t going to defect into liberalism, generally. To this day, many Evangelical Protestants see the ‘official’ public policies of the Catholic Church involving economic issues in much the way Cardinal Ratzinger viewed Liberation Theology in the 1980’s. (I don’t feel this way but know that a number of Protestants have denounced papal pronouncements on economic issues to be nought more than ‘communism’). Protestants are often appalled at the modern-day opposition of the RCC to the death penalty.
All of this aside–the Roman Catholic Church is the biggest single denomination in most Western countries, and being able to forge alliances with it on most of the hot-button issues of the hour pleases Evangelicals. It helps us to keep pressure on our political leaders, who otherwise feel little compunction about abandoning Evangelicals when the chips are down. Most of us liked Pope John Paul II’s conservativism and like Ratzingers as well. Moreover-- the fact that the RCC is seen as an apostate charicature of the Christian faith scarcely means that it is as bad an institution as it could possibly become. The whole point of the “Left Behind” novels was that the RCC could become an even worse instrument for terror if ever it were again fully yielded over to Satan’s purposes as once it was in the days of the Inquisition. (Please note that I am not expressing my OWN view of the RCC–which is rather much more positive–but views I have seen bandied about in various and sundry forms among many Protestants).