This was Jesus lesson during his ministry (Matthew 22:37-39) -- Love God with all your heart and love your neighbor as yourself. Those are the two greatest commandments which are equally important and encompass the entire law of the Old Testament.
The Bible is one entire story -- the Old and New Testament connect together. Jesus gave two commandments that both covered and went beyond the Old Testament. Jesus repeats Deuteronomy 6:5 when presenting the new, simplified commandments in Mark 12:30, tying the old to the new. God kept his promises in the old days and he continues to keep them now.
Thank you for sending your son and keeping your promises. I love you with all my heart, soul and strength. Help me to also love my neighbor as myself and keep your commandments above all else.