You are avoiding discussing the problem statement. Rick Santorum said that as President he was going to do what no other President before him has done, and that is to talk about why contraception is "not okay". THAT is the problem. Had he just said he's Catholic and personally agrees with the church there would not have been much of an issue. Had he joked about it like O'Reilly and you suggest and said "hey, Ive got 7 kids so I don't know much about it", there wouldn't have been much of a problem. Where Santorum screwed up is by outright saying one of the things he would do as President is talk about why contraception is "not okay"
Here is the quote which is the one that was on video and got him in so much trouble:
One of the things I will talk about that no President has talked about before is I think the dangers of contraception in this country, the whole sexual libertine idea. Many in the Christian faith have said, 'Well, that’s okay. Contraception’s okay.' It’s not okay because it’s a license to do things in the sexual realm that is counter to how things are supposed to be.
Santorum never walked that back. No, he wasn't ever talking about banning contraception, but he did want to talk about, as President, why it was "not okay". I'm sorry, but that isn't the President's job. The public is never going to elect a candidate who says these sorts of things at this time. Who knows what the future holds, maybe some virus will kill half the public and society will find a pressing need to have many more babies. If that happens, Santorum's views might make him electable. But right now, no, not a chance. He should never have said that.
However, I can't blame Santorum for saying something that is consistent with his conservative Roman Catholic position. It was going to come out no matter what — unpopular faith-based positions always get trotted out for attention in campaigns if the candidate is a devout believer, and it's going to be happening soon with Romney's Mormonism. What Santorum did was link contraception with rampant sexual immorality, and that's an issue on which most conservative Christians will agree with him no matter whether they agree on contraception or not.
That linkage can be defended easily by pointing out that the liberals love sexual freedom based on the widespread availability of contraception, with abortion as a backup if it doesn't work.
As an evangelical Protestant who is not convinced birth control is sin, I'm not going to say what Santorum said. But I have equally unpopular religious views which I would not back down from if the issues were to be raised in a political campaign.
Being honest and being willing to offend people in a campaign is not something that annoys me in a conservative politician. The same forthrightness that got Santorum into trouble is what got him a lot of votes, including from people who didn't agree with him on the contraception issue or his fundamental Roman Catholic beliefs.
I believe Santorum could have recovered from the contraception issue. Most people who strongly opposed him on that wouldn't have voted against him anyway in the primary, but would have voted for him in the general election on the grounds that Obama is far worse.
I can't say that about Mitt Romney.