Belial definition
Belial in the Hebrew, literally means "worthless" or "wicked" (evil), reckless, lawless, destructive. Belial is the spirit of destruction, and, in actuality, represents Satan's ministry (John 10: 10) The spirit of Belial is the driving force behind the sons of Belial, those human agents who willfully give themselves over to a depraved mind, full of every evil intent, without conscience or remorse. The word "sons" in the Hebrew, literally refers to the "men" of Belial. In other words, they take on the life of the spirits who drive them. They are, in other words, possessed. They have permitted the spirits of Belial to live their lives in them and through them, a Satanic counterfeit of what yielded Christians do when they allow the Holy Spirit to live His life in them and through them. They (the men) have become empty vessels for their (the spirits) use. The spirit of Belial is on each and every such person who has permitted a certain area of their thought life to be possessed by this spirit, and in so doing, has given himself/herself over to obsession to do harm and evil (wickedness). The spirit of Belial, the spirit of terrorism, and the spirit of witchcraft are the three fold cord which drives the terrorist under the direction of the antichrist spirit. The spirit of Python (divination) is a co conspirator, as is the spirit of religion and the spirit of obsession.
Belial means worthlessness, as an epithet of Satan. That is exactly what Satan is, worthless. All the comparisons above are opposites. Christ and Satan are opposites. "Infidel" means disbelieving. The answer is that they have nothing in common.
Belial means worthlessness. David is saying that just as you would gather up thorny bushes and burn them to keep them from ruining the crop, the worthless people should be dealt with harshly. He cannot judge them kindly, they have to be destroyed.