Matthew 22:37

‘And he said to him, “You shall love the Lord your God with all your heart, and with all your soul, and with all your mind.”

Jesus went right to the heart of the matter, citing Deuteronomy 6:5. This could hardly fail to meet with their approval for it was in fact a verse which was central to Jewish worship, and repeated by every good Jew each day. It was considered so important that it was carried around in the phylacteries worn by Pharisees on their heads and arms and fixed to their doors in small tubes (on the basis of Deuteronomy 6:8, interpreted literally). They would thus not have doubted its great importance. And this verse points out that the most important of God's requirements is that we love Him ‘with heart and soul and mind', in other words with the whole of our inward beings. (Mark also has ‘and mind', and adds ‘and strength' which is found in Deuteronomy. Deuteronomy, however omits ‘mind', although having said that, mind is included within the Old Testament idea of the ‘heart'. Thus all the descriptions intertwine, for where a man's heart and soul and mind are involved, so also is his strength). So Jesus was saying that this love for God lies at the heart of all true worship, and of all true morality. But what are to understand by ‘loving God'. It indicates the kind of response that longs for God and continually owns His worth, and thus longs to please Him and do His will because of His total worthiness. But it also includes along with that the idea of trusting Him fully and serving Him truly And once this command is in place and observed all the rest truly  is  commentary, for it embraces all that God requires of us. Once a man or woman loves God like this their whole lives will be lived in order to please Him, and they will seek to be ‘perfect' even as He is ‘perfect (Matthew 5:48).

Putting the idea of a heartfelt relationship with God as lying at the root of man's behaviour is not a new concept. The idea can also be found in Deuteronomy 10:12; 1 Samuel 15:22; Isaiah 1:11; Isaiah 43:21; Isaiah 44:5; Jeremiah 31:33; Ezekiel 36:26; Hosea 6:6; Amos 5:21; Micah 6:6.