God’s commands in the Old Testament and Jesus’ commands in the New are one and the same, in truth and in purpose. They are both meant to show us what is right and wrong, the difference between temporal and eternal. They are both meant to give show us what is best for eternity, and to show us how to become perfect vessels for the Father.
The Father in the New Testament is the same Father in the Old Testament (though He is rarely referred to as that in the Old Testament). Both Testaments give a view of what a true relationship with the Father is. In fact, Jesus restates the Deuteronomy command to “love the Lord your God with all your heart and with all your soul and with all your strength.” That’s where it all lies, in loving the Father.
Looking at the first four of the Ten Commandments, all of them deal with our relationship with God the Father, yet all are fulfilled if we remember this one thing: to “love the Lord your God with all your heart and with all your soul and with all your strength.” If we love Him that much, we will have no other gods before Him. We will not serve anything other than Him or try to put Him in a box. We will not take His name in vain or treat Him vainly or as unimportant, for our relationship with Him must be uninhibited. We will take time to cultivate our relationship with Him and remember what He has done for us, collectively and individually.
If we love Him with all our heart, we will honor Him and live for Him, and love Him, as He has called us to do. Then, as Jesus told us, He will give us the eternal, God-given desires of our hearts, and all the other worries and fears and needs will be taken care of in time. God is to be our all; if He is in everything we do, eternity goes with us.