Deuteronomy 6:4-5
Hear, O Israel: The LORD our God is one LORD: And thou shalt love the LORD thy God with all thine heart, and with all thy soul, and with all thy might.

Why is this considered the greatest commandment?  Why would a call to love God be more important than the list of commandments Moses had just told the people about?  It is because without love, obedience is impossible.  Yes, we can stick to something for a time out of our own will, maybe a sense of duty, but when what we love more comes along, that will pull us away.  If we don’t love the God who gave those commandments, what incentive is there to follow through in obedience?  What motive is there to do things we are not otherwise inclined to do?

What else but love for another could wind its way into our hearts and pull out of us those desires we have to only serve self or to find satisfaction at any cost?  Love raises the bar.  Love introduces another person into the equation.  And there is no stronger motivator because there is no stronger emotion, no stronger force.  It is, after all, the force that set in motion God’s whole plan of salvation in the first place.  It was His motive for giving this law to the nation of Israel.  It was because of His love that He sought to be a part of their lives, to dwell in their midst, to be their one and only.

What we set our hearts on dictates much about the course of our lives.  If we love money, we’ll pursue it to our own destruction.  If we love fame and attention, we’ll do whatever we can to get it.  If we love pleasure and the things of this world, we’ll invest all we have into those things and reject anything that says we can’t have them.  If we love other people most, our devotion is to them at the expense of our relationship with God.  All of those things push God out for something else, and suddenly doing what He wants us to do doesn’t matter so much, and serving Him isn’t even something we’ll consider, and giving Him glory hurts us because we don’t want to share it with Him.

But when we love God like we were created to love Him—with all that is in us, to the fullest—that changes how we act, what we do, where we go.  When we love Him that much, when He becomes our focus and the object of our desire, what a difference that makes.  Then obedience is joy, service a privilege, and glorifying Him becomes our one desire because we adore Him so much.  So, where is our heart, and where is our love?  If another true love has superseded our love for God, it will affect our choices, our obedience, and our fellowship with Him.