It's a combination of many columns, so I can't even say "a little bit of column A and column B"
Aspects include:
1. The need for control
2. Psychological issues
3. Tradition. The man is the king of his household, and all within are his subjects and must follow his rule. Disobedience brings about punishment. (Also, 1.)
4. The idea that being non-violent is weak and for spineless cowards.
5. The idea that if they aren't feeling pain, it isn't discipline - parents who "only" lock kids in their rooms are weak-willed cowards who are spoiling their kids.
6. They had the same thing done to them when they were kids. They feel like they deserved it. Because if their kids don't deserve it, maybe they didn't.
7. A misinterpretation of "Thou shalt not spare the rod" (namely, "rod" in this case referring to a Shepherd's crook that is used to pull sheep onto a corrective course or save them from danger - you're not supposed to hit sheep with them, though I imagine shepherds did, in fact, do so.)
8. Instilling the literal fear of God into one's children, because Love of God is to Fear him. If they do not Fear god, then they are going to hell, and that is a bad thing.
9. Anger that is not healthily expressed.
10. Because it deserves a second mention, desire to have control. Especially in light of 6, where they did not have control, but now they do.
Corporeal punishment is the most psychologically harmful discipline out there - but science that contradicts God is Evil and of Satan. And so, they carry on harming their children for life because they think they're doing the right thing for them.
Abusers often believe they are doing what's right for the people they're abusing. "She needs to be with me, she needs to be put in her place, she needs me to run her life for her, because she can't do it herself. She needs me. And what I'm doing is good for her."