The Ten Commandments are listed in full in Deuteronomy. The first is given in Deut. 6:5, and instructs us to, ‘Love the Lord our God with our heart, and with all our soul and with all our strength’. It is well known that Jesus added to this commandment centuries later, when he gave the ‘New Commandment’ to love each other as Jesus himself had loved his disciples. The giving of the New Commandment is recorded in John 15:12.
But what is not so well appreciated is that Jesus was more radical and actually rewrote the first commandment. Look at Mark 12:28–31, which is an account of Jesus debating with the teachers of the law. Noticing that Jesus gave good answers, one of the teachers asked him which was he greatest commandment, and Jesus answered, ‘Love the Lord your God with all your heart, and all your soul, and all your mind and all your strength.’ Jesus added a fourth way of loving God: with our minds.
We are to understand that following Jesus is not a matter of learning a series of rules by rote and following each of them mechanically. God does not want us to be robots. In fact, to ‘love God’ by following a list of rules was the way that Jesus condemned the Pharisees for.