24 ‘By these you shall become unclean; whoever touches the carcass of any of them shall be unclean until evening; 25 whoever carries part of the carcass of any of them shall wash his clothes and be unclean until evening: 26 The carcassof any animal which divides the foot, but is not cloven-hoofed or does not chew the cud, is unclean to you. Everyone who touches it shall be unclean. 27 And whatever goes on its paws, among all kinds of animals that go on all fours, those are unclean to you. Whoever touches any such carcass shall be unclean until evening. 28 Whoever carries any such carcass shall wash his clothes and be unclean until evening. It is unclean to you.
29 ‘These also shall be unclean to you among the creeping things that creep on the earth: the mole, the mouse, and the large lizard after its kind; 30 the gecko, the monitor lizard, the sand reptile, the sand lizard, and the chameleon.31 These are unclean to you among all that creep. Whoever touches them when they are dead shall be unclean until evening. 32 Anything on which any of them falls, when they are dead shall be unclean, whether it is any item of wood or clothing or skin or sack, whatever item it is, in which any work is done, it must be put in water. And it shall be unclean until evening; then it shall be clean.33 Any earthen vessel into which any of them falls you shall break; and whatever is in it shall be unclean: 34 in such a vessel, any edible food upon which water falls becomes unclean, and any drink that may be drunk from it becomes unclean. 35 And everything on which a part of any such carcass falls shall be unclean; whether it is an oven or cooking stove, it shall be broken down; for they are unclean, and shall be unclean to you. 36 Nevertheless a spring or a cistern, in which there is plenty of water, shall be clean, but whatever touches any such carcass becomes unclean. 37 And if a part of any such carcass falls on any planting seed which is to be sown, it remains clean.38 But if water is put on the seed, and if a part of any such carcass falls on it, it becomes unclean to you.
39 ‘And if any animal which you may eat dies, he who touches its carcass shall be unclean until evening. 40 He who eats of its carcass shall wash his clothes and be unclean until evening. He also who carries its carcass shall wash his clothes and be unclean until evening.
41 ‘And every creeping thing that creeps on the earth shall be an abomination. It shall not be eaten. 42 Whatever crawls on its belly, whatever goes on all fours, or whatever has many feet among all creeping things that creep on the earth—these you shall not eat, for they are an abomination. 43 You shall not make yourselves abominable with any creeping thing that creeps; nor shall you make yourselves unclean with them, lest you be defiled by them. 44 For I am the Lord your God. You shall therefore consecrate yourselves, and you shall be holy; for I am holy. Neither shall you defile yourselves with any creeping thing that creeps on the earth. 45 For I am the Lord who brings you up out of the land of Egypt, to be your God. You shall therefore be holy, for I am holy.
46 ‘This is the law of the animals and the birds and every living creature that moves in the waters, and of every creature that creeps on the earth, 47 to distinguish between the unclean and the clean, and between the animal that may be eaten and the animal that may not be eaten.’” Leviticus 11: 24-47 NKJV
Was it because some of these animals were reverenced as idols, or that they were used in pagan ritual, as some have speculated? Well, I tend to lean away from this, because as the Creator, all the above mentioned creatures belong to God anyway, no matter what men should think or say about them. Besides, bulls, cows, rams and goats all found their way into pagan culture and worship, just like swine, rabbits and crocodiles. When all these things that were called unclean became instead a part of our liberty, had anything changed about them, or did they in fact represent the volition of God, his timing and work? I think scripture is the best interpreter of scripture, and when we read the Old Testament we will often see those things that are our teachers, like the law which convicts of sin, the dietary laws that teach of clean and unclean, separation and the right of God. If there is to be a change in the law then this should also come from God, and be understood because of the fulfillment of His divine work in that dispensation. Sin still exists, and as previously discussed, a Holy and eternal God, is going to remain infinitely opposed to sin. He is also, according to His Word, a God of order and not of confusion, so He breathed His word to those who penned it, with His intent.
7 When He had entered a house away from the crowd, His disciples asked Him concerning the parable. 18 So He said to them, “Are you thus without understanding also? Do you not perceive that whatever enters a man from outside cannot defile him, 19 because it does not enter his heart but his stomach, and is eliminated, thus purifying all foods?”[a] 20 And He said, “What comes out of a man, that defiles a man. 21 For from within, out of the heart of men, proceed evil thoughts, adulteries, fornications, murders, 22 thefts, covetousness, wickedness, deceit, lewdness, an evil eye, blasphemy, pride, foolishness. 23 All these evil things come from within and defile a man.” Mark 7:17-23
The sin that could arise here would not be inherent to the above mentioned animals, but rather from the heart of a disobedient people. When I was young and had no real desire to understand these things or follow God's word, I would always assume that what I did not immediately understand was foolishness. Why does God even concern Himself with what I eat, and why does he tell these people to do all these things? Who cares if I am proud? Pride is a good thing, right? I am going to go out on a limb here and suggest that God says things for a reason, and that when He promises a Savior in the Old Testament, you will see a baby in a manger when that New Testament dispensation occurs. In fact, all of the old Testament cries out for the New and in the New we receive the clarification of the dietary laws, and our eyes are opened a bit more. So when someone comes swinging their fists, asking me why I eat pork or watch a sport that uses a ball made out of a pigskin, I have to smile, because I do eat bacon, but I don't watch football, it's just not that interesting.