Cleanness Clean 
Because the mind is an integral aspect of the human personality, cleanness must also be applied to attitudes and motives that govern particular forms of behavior. Impure thoughts as the expression of the mind can result in shameful activities ( Mark 7:15 ) unless they are checked firmly, and bring disgrace to the individual concerned as well as harm to others. A “clean-living” person is generally understood to be one who does not give evidence of being a criminal, a victim of such vices as alcoholism and drug addiction, or an individual who habitually flaunts God's moral code.
Cleanness, however, is a relative term when the human condition is being considered. Mankind's fall from divine grace as a result of defying God's commands and yielding to temptation has made sin a genetic issue ( Genesis 3:1-19 ). This means that the tendency to sin is inborn, with the inevitable result that, as the ancient psalmist said, there is none righteous ( Psalm 14:3; Romans 3:10 ). Paul stated the situation with equal emphasis by proclaiming that all have sinned and come short of God's glory ( Romans 3:23 ). Human sin places a barrier between sinners and a just, holy God. Sinners are unclean in God's eyes.
The religious rituals of Leviticus had much to say about the way in which the sinner could be cleansed from iniquity and be reconciled to God. This was a matter of great importance to the Israelites, because God required them to be a kingdom of priests and a holy nation ( Exodus 19:6 ). In the Ancient Near Eastern religions the idea of holiness was applied to a person in a state of consecration to the service of a deity, whose cultic worship could, and frequently did, involve acts of a gross sexual nature. For the Hebrews, holiness demanded that they should reflect in their living and thinking the exalted moral and spiritual qualities of God as revealed in His laws.
Cleanness was thus fundamental to the establishing and preservation of holiness in the Israelite community. As distinct from all other nations, the Hebrews were provided with specific instructions concerning cleanness and how to recover it when it had been lost through carelessness or disobedience. The principles of cleanness touched upon all aspects of individual and community life. They were ultimately capable of a moral interpretation, since in the holy nation secular and spiritual matters were closely connected.
God established for the Israelites a special group of laws dealing with clean and unclean animals ( Leviticus 11:1-47; Deuteronomy 14:1-21 ) to provide guidance for dietary and other circumstances. While the nations of the Ancient Near East maintained a general distinction between clean and unclean species, the principles of differentiation were in no sense as explicit as those provided for the Hebrews. Clean animals were allowed to be eaten, but unclean ones were prohibited strictly. The terms “clean” and “unclean” were defined by illustration, and clear principles were enunciated to enable anyone to make the distinction correctly.
Very simply, whatever animal had a cleft hoof and chewed the cud was clean, and therefore suitable for food. Any animal that did not meet these specifications was unclean, and consequently was not to be eaten. If an animal such as a camel possessed only one of the two stated requirements, it was still regarded as unclean. Because birds formed part of the Israelites' diet, a list of those species suitable for food excluded the ones that might carry communicable diseases.
There has been much discussion about the purpose of these regulations. Some writers claimed that they were designed so as to avoid pagan idolatrous practices. Others have focused upon preserving the separated nature of the Israelites in matters of food as well as in ethical and religious considerations. Yet another view emphasized the hygienic aspects of the laws as a means of preventing the spread of infectious ailments. Most probably, all three concerns underlay the legislation, and therefore each should be given due weight. Animals associated with pagan cults were prohibited, as were unfamiliar or repulsive creatures, and those species that fed upon carrion. If the rules for food were followed, the Hebrews could expect to enjoy good physical health. Clearly the overall objective of the dietary laws was the prevention of uncleanness and the promoting of holiness in the community ( Leviticus 11:43-44 ).
Uncleanness also applied to certain objects and situations in life which conveyed impurity to those involved. Thus contact with a dead person ( Leviticus 5:2; Leviticus 21:1 ), a creeping insect or animal ( Leviticus 22:4-5 ), the carcass of an animal ( Leviticus 11:28; Deuteronomy 14:8 ), or a woman in labor ( Leviticus 12:4-5 ) brought about uncleanness, which required ritual purification to remove it. Leprosy was particularly dangerous as a source of uncleanness, and required special cleansing rituals ( Leviticus 14:13 ) when the sufferer was pronounced cured. Unclean persons transmitted their condition to whatever they touched, so that others who handled such things became unclean also. Even God's sanctuary needed to be cleansed periodically ( Leviticus 4:6; Leviticus 16:15-20 ).
As noted previously, cleanness had a specific moral dimension. Because God's priests were to be clothed with righteousness ( Psalm 132:9 ), the entire nation was involved in manifesting the priesthood of all who believed sincerely in the covenant relationship with God that had been forged on Mount Sinai. Thus to be clean meant not merely the negative aspects of being free from disease or defilement, but the positive demonstration in daily life of God's high moral and ethical qualities of absolute purity, mercy, justice, and grace.
Cleanness was a part of the moral stipulations of the Law. Thus murder was both a pollution of the land and a violation of the Decalogue's express commands. The killing of the innocent called for a response in justice from the entire Israelite community, based upon a principle of blood retribution ( Numbers 35:33; Deuteronomy 19:10 ). Grave moral offenses that violated God's law and polluted the nation included adultery ( Leviticus 18:20 )—a capital offense ( Leviticus 20:10 )—and perverted sexual activity which included bestiality, with death as the prescribed punishment ( Leviticus 20:13 ).
Ceremonial holiness thus involved distinguishing between clean and unclean. Moral holiness required the Israelites to behave as a nation separated from the pollutions of contemporary society, and to live upright and righteous lives in obedience to God's laws ( Leviticus 21:25-26 ). For the penitent transgressor a complex system of purificatory rites cleansed from both physical and moral defilement. These involved various kinds of washing by water, as a natural cleansing process ( Leviticus 6:28; Leviticus 8:6; Leviticus 14:8-9; Numbers 8:7; Numbers 19:9 ); the use of ashes ( Numbers 19:17 ) and hyssop ( Numbers 19:18 ) for ritual and accidental contamination; and sacrificial blood, which made atonement for sin and reconciled the worshiper to God. The Law established the principle that blood made atonement for human life ( Leviticus 17:11 ), and thus a blood sacrifice involved the highest form of purification ( Leviticus 14:6 , Leviticus 14:19-20 ) or dedication to God ( Leviticus 8:23-24 ). Yet even this form of sacrifice was powerless against sins deliberately committed against the spirituality of the covenant ( Numbers 15:30 ).
In the New Testament, cleansing was associated only with the ritual customs of contemporary Judaism. Thus the infant Jesus was presented in the Temple for the traditional purification ritual ( Leviticus 12:2-8; Luke 2:22 ). Cleansing ( katharismos ) was a matter of contention between the Pharisees and the disciples of John the Baptist ( John 3:25 ), but Christ obeyed the Law in sending healed lepers to the priest for cleansing ( Leviticus 14:2-32; Matthew 8:4 ). On other occasions He asserted His superiority to the ordinances that He would subsequently enrich and fulfill ( Matthew 12:8; Mark 2:28; Luke 6:5 ).
In His teaching Christ made the Old Testament cultic regulations concerning cleanness even more rigorous by stressing a person's motivation rather than the external or mechanical observance of rules and regulations. He taught that adultery had been committed just as fully by a man's lusting after a woman ( Matthew 5:27-28 ) as if the physical act had occurred. In John 15:2 , the word that Christ had proclaimed made them clean by regenerating their characters and inculcating holiness of life.
Jesus was not only a moral Teacher. He came to earth to give His life as a ransom for humanity's sin ( Mark 10:45 ). In this way He became the Lamb of God, taking away the sin of the world ( John 1:29 ). His atoning death as our great High Priest transcended all the Law's cleansing rituals could ever be expected to do in the single offering of Himself for us on Calvary ( Hebrews 7:27 ). There He instituted a New Covenant of divine grace in His blood ( Hebrews 8:6 ), achieving human redemption and making possible eternal life for the penitent individual who has faith in His atoning work.
One of the most gracious assurances of His New Covenant is that the blood of Jesus cleanses us from all sin ( 1 John 1:7 ). Sacrifices and offerings are now unnecessary, for what Jesus demands is a penitent spirit that confesses the merits of His atonement. For the Christian the cultic provisions of the Old Testament are nullified. All meats have been declared clean ( Mark 7:19; Acts 10:9-16 ), and the only sacrifices that God requires are those that emerge from a humble and contrite heart ( Psalm 51:17 ).