You probably won’t be surprised to know that there is much debate about this. Here are some of the suggestions:

1. Some regulations seem designed to prevent the Israelites from indulging in the religious practices of the pagan Canaanite nations. E.g. the regulations about sex and contact with corpses prevent cult prostitution and ancestor worship.

2. Many of the ‘unclean’ things are related to weakness, illness or death (e.g. decay, loss of blood, animals that feed off carrion, etc.). Holiness is about life and wholeness. There is something symbolic going on here.

3. There could be a health-related element, too. The ritual washing keeps up levels of personal (including sexual) hygiene. The ‘clean’ animals in many cases are the ones least likely to cause food poisoning or other illnesses.

These are just three possibilities, and it’s quite possible that the true answer is a combination of these and more. What we do know is that this idea of holiness and purity was woven into the everyday life of every Israelite. Every day carried many opportunities to live out and develop loyalty and obedience towards God.

Jump ahead to Mark’s gospel and we can see something of the radical nature of Jesus’ ministry (something the Pharisees hated). He effectively declares all foods clean (7:19). He touches a dead girl and is touched by a woman whose bleeding makes her ‘unclean’. But instead of becoming unclean himself, he gives them life and wholeness (5:21-43). In the same way, he touches someone with leprosy and makes them well / whole / clean (1:40-45). The laws of Leviticus were not wrong. They were right for their time and place. But Jesus is bringing in a new era (‘the kingdom of God is near’). He has come to make the unclean clean, the impure pure, the unholy holy. And he does that for us, too.

Leviticus answers the question of how the people of Israel are to worship a holy God, and a major part of that is maintaining their own holiness, or purity. 11:44 encapsulates this well: ‘I am the LORD your God; consecrate yourselves and be holy, because I am holy.’ 

In Leviticus, holiness is maintained by a combination of rituals (sacrifices and festivals) and regulations (e.g. about which foods are ‘clean’ and which are ‘unclean’). The detailed practice of these has been superceded by Jesus (see Mark 7:14-23 and most of Hebrews) but the call to be holy remains and is echoed in the New Testament – see 1 Peter 1:15-16 (where Leviticus is quoted and applied to Christians) and Matthew 5:48 (‘Be perfect, therefore, as your heavenly Father is perfect.’) For the Christian, purified by the blood of Jesus, living a holy life is encapsulated by the command to love others as God has loved us (see 1 Peter 1:13-25).

Mark is the shortest of the gospels and regarded by many (but not all) scholars as the earliest. In comparison with Matthew it is short on the teachings of Jesus and long on action. It also proceeds at a cracking pace, as you’ll notice straight away in chapter 1. One theme to look out for is discipleship. As you read through, can you imagine what life with Jesus was like for those first disciples? Watch out for their responses to him. How does their experience of Jesus compare to yours?