Here’s what I get from his thinking:
Abortion shouldn’t be permitted in the cases of “legitimate”, i.e. forcible rape because women don’t get pregnant anyway (magic fairy dust?).
Abortion shouldn’t be permitted in cases of statutory (i.e. illegitimate) rape because it’s, well, “illegitimate”.
The use of the word “legitimate” was not a gaffe. It was fully intentional because it fits his rationale as to why abortion should be illegal in all cases.
But, after the fact, he and his defenders are claiming the word “legitimate” was a gaffe and he really meant forcible.
It wasn’t a gaffe. He meant it that way.
And finally he said the God-given truth that abortion is always wrong because the baby is an innocent who doesn't deserve to be punished for the actions of anyone else. If you believe people should have the right to butcher unborn babies in the womb, please state that clearly so we know why you might REALLY oppose Akin.