Hardly wishing to defend Kristof I would nevertheless point out that this author seems to be somewhat ignorant of Conservative ethics of yesteryear. Yes, he briefly mentioned Kristof's assertion that conservatives only began to care about abortion in the 1960's and 1970's, but he doesn't interact with it. Instead he turns to Church History.
In terms of Church History the Church's record on 'life' issues is rather mixed and the subject is something of a tangle. The testimony of Scripture and the Early Church is pretty clear and personally I am content to leave it there. The New Testament and the Early Church were clearly against abortion and killing of any kind for that matter.
After chuckling my way through the comments I guess I'll risk sounding 'liberal' to point out that Conservatives are largely ignorant of their own past and their past views of race, education, housing, immigration and certainly birth control and eugenics. There are whole chapters of American social history that have been whitewashed and ignored and for those that do not have memories which extend past the birth of the Christian Right in the 1980s and 1990s, the past will seem strange indeed.
While I don't think Protestant Evangelicals (let's be a little more specific than just 'Christian') were necessarily championing abortion before Roe v. Wade, the truth is, it wasn't an issue of great importance. Falwell and other early architects of the Christian Right are on the record in admitting this. It was a Catholic issue. Why?
Well, that's another story and it goes back to the issues surrounding massive Catholic immigration and battles over everything from education to local politics in the early 20th century. This is why many conservative, Nativist-minded and even professing Christian people (whatever is meant by that) supported birth control as a means of suppressing the non-Anglo Saxon Protestant populations. It's a shameful chapter and a confusing one.
The answer isn't to revise the history but to learn from it and in this case understand what set of beliefs drove the Church to the point that many within it embraced this type of thinking.