The command to love God with all of the heart in the Shema (Deut 6:4-5) was given in a context where many gods were worshiped. The pagans believed in multiple gods and had to always save room in their heart for another god. But for Israel there is only One and no other. So we are to love God with an undivided heart and with our whole being. A divided heart always has an idol lurking in the shadows somewhere.
“Moreover the Lord you God will circumcise your heart and the heart of your descendants, to love the Lord your God with ALL your heart and with all you soul, in order that you may live” Deut. 30:6.
