I agree with you 100%. I don’t see how any true evangelical could support gay civil union/marriage. As I understand it, the term “evangelical” refers to Christians who believe that the Bible means what it says. Thus, in both the Old Testament and the New Testament where it says a man shall not lie with a man as with a women, that’s a pretty clear statement against the practice. One cannot, therefore, proclaim to be an evangelical and support gay marriage, unless one is, as you say, an “infant Christian,” who is ignorant of scripture. It just doesn’t follow.
Wouldn’t Bill Clinton fit some definition of “Evangelical” wasn’t he seen coming out of church once with a huge Bible under his arm?