A wife can have it tough sometimes. Jesus commands her to submit to her husband. He also expects her to discipline her children. What does she do when those two commands appear to conflict? How does she handle a 4-year old son who won’t obey and a husband who doesn’t think that spanking works?
It can be dangerous to answer these questions without learning more about the situation, the marriage relationship, the husband’s understanding of discipline, the wife’s understanding of discipline, the actual disobedient behavior of the boy, and so on. A one-size-fits-all approach is probably not very wise. But I will offer some general principles.
Assuming the boy’s rebellion is the typical 4-year-old sort (and not the cursing-at-mom-while-trying-to-dangle-his-little-sister-ten-feet-over-the-stairwell sort), I believe that the call to submission is prior to the call to spank. If she undermines dad’s authority, not only is she sinning, she is also setting an example for the child which will lead to further disobedience down the road (more like the stairwell kind). The wife should seek a loving conversation with her husband in which she explains her concerns without using disrespectful, accusatory words or tones. She is right to be troubled by her son’s unruly behavior, and she is right that spanking is the Bible’s intended means of discipline. But she is not free to take matters into her own hands in direct defiance to her husband. He is the head of the home and she should comply unless he requires her to commit sin.
That’s just the thing, though, isn’t it? If spanking is biblical, isn’t he asking her to sin by keeping her from it? Probably. If so, he will have to answer to Jesus for it. But discretion is also required. If he is supportive of discipline, just not spanking, the wife should pursue all “allowable” means of discipline and acquiesce to his no-spanking rule, all while praying for her husband’s repentance. In this case, she should follow the examples established in 1 Peter 3:1-6. (If he is opposed to all disciplinary measures, she should seek counsel from their elders.)
One last thought. If her husband is not directly opposed to spanking but is simply unconvinced of its effectiveness, the wife should spank firmly, consistently, relentlessly, and lovingly. Immediate bodily discipline combined with tender affection and forgiveness will usually lead to a well-behaved child. This, better than anything else, will persuade her husband.