Let's make clear, it is not the case that most religious believers, or most Christians, or even fundamentalist Christians, believe that God supports this sort of cruelty to children. But there seems to be an element within some branches of fundie Christianity which strongly approves of 'breaking children's will', at whatever price.
In particular, these 'parents' seem to have been influenced by the writings of the Pearls, which are incredibly nasty and dangerous.
Read this and weep:
http://www.nogreaterjoy.org/articles/general-view/archive/2001/may/01/in-defense-of-biblical-chastisement-part-1/Excerpts:
'Without the rod you are giving the child a false concept of the nature of God. God does hate sin, and he is to be feared. The Bible says, “The fear of the LORD is the beginning of wisdom (Psalm 111:10).” And again, “The fear of the LORD is the beginning of knowledge (Proverbs 1:7).” “The fear of the LORD is clean, enduring for ever: the judgments of the LORD are true and righteous altogether (Psalm 19:9).” Many people, especially religious people, take offense to the Biblical teaching that God is to be feared. Yet we all fear government, the state trooper, the IRS, and any temporal institution that has the power to punish offenders. We are to fear God as a man in the military fears his commanding officers. Without such fear there would be no discipline, and the armed forces would be rendered ineffective. A man in the army may both fear his sergeant and love him at the same time. The fear comes from the power he wields. The love comes from the deep respect the soldier has for the man that gives him self-respect by forcing him to excel.
As governor of the universe, God has revealed his platform, his constitution, and his agenda. He is narrow minded and decisive. He is not subject to change or negotiation. His laws are unalterable, and the consequences for breaking them are certain and final. He is not an activist judge who reinterprets his laws to fit the changing majority opinions. He is “the same yesterday, today and forever (Heb 13:8).” “It is a fearful thing to fall into the hands of the living God (Hebrews 10:31).”
The rod mirrors judgment to come.
.... We do not believe that when small children die they are in jeopardy of hell. We believe there is a special dispensation for those who have not matured into a consciousness of accountability. Yet all adults learned the rules of society and God when they were very young, before they reached a condition of accountability. If parents allow their children to be unruly, never forcing them to obey, to conform to the rule of law, by the time the child is old enough to understand his accountability, he will already have developed a world-view that assumes there is no day of reckoning, no punishment for doing evil, only more threatening words. People have an overwhelming tendency to live by the principles they learned before the age of six.
Though children cannot understand coming judgment, they must be trained to make decisions with consequences in mind. If you allow the child several years of living without consequences, it is difficult for him to ever accept the truths of coming judgment, the character of God, and the nature of sin. The swift and just application of the rod causes the child to believe that all evil is punished and that one cannot get away with sin. Whatever you sow you will reap.'
And from another article:
'If you are seeking to avoid the rod because you are an emotional coward or you are a product of contemporary philosophy, then not obeying God in this matter should not be considered an option. The Word of God teaches us the best method of child training, and proper use of the rod is a part of that program. Furthermore, if you abstain from use of the rod because you believe there is a better way, then you have revealed a fundamental flaw in your thinking that will leave a giant hole in any method you adopt. In other words, a person who understands the value and principle of the rod, but is somehow prevented from using it, will carry those valuable principles over into rodless training and so reap some of the benefits. Whereas the person that does not believe in use of the rod is so flawed in his understanding of human nature and life in general that no technique will be entirely effective for him.'
And from another:
'How many licks?
There is no number that can be given. It would be better to administer more licks that are less forceful than to administer few licks that hurt severely. It is much more effective to administer chastisement or punishment in a slow thoughtful fashion. Our goal is to cause the child to voluntarily surrender his will. We want to impress upon him the severity of his disobedience. It takes time and thoughtfulness for the child to come to repentance. I have told a child I was going to give him 10 licks. I count out loud as I go. After about three licks, leaving him in his position, I would stop and remind him what this is all about. I would continue slowly, still counting, stop again and tell him that I know it hurts and I wish I didn’t have to do it but that it is for his own good. Then I would continue slowly. Pretending to forget the count, I would again stop at about eight and ask him the number. Have him subtract eight from ten, (a little homeschooling) and continue with the final two licks. Then I would have him stand in front of me and ask him why he got the spanking. If his answer showed that he was rebellious and defiant, he would get several more licks. Again he would be questioned as to his offense. If he showed total submission, we put it all behind us, but if he were still rebellious, we would continue until he gave over his will. Only about three of our five children ever resisted after a spanking and refused to cooperate. Each of the three required only one experience of continued spankings until they surrendered. None of the three ever tried it a second time. In all cases, it was between the ages of two and four that they tried their moment of defiance.'
This is all REALLY scary!