Apparently they believe that parents have a God-given right to wield authority over their children, which can include physical chastisement: what the Christian Institute calls “a loving smack”

When are we going to stop legally hitting kids in Northern Ireland? It’s outrageous that the law continues to provide for it.
Scotland banned smacking in 2020, and Wales followed suit in March 2022. Yet in England and Northern Ireland, the defence of reasonable punishment is still allowed.