All sin can be traced back to a selfish heart. Every offence against someone is because someone considered themselves more important. Everything we have ever done against God happened because we considered what we wanted more important than what God wanted. We are a people who say we want to love God but we don't know how to let go of ourselves to do it.
We can look at all the socio economic reasons why we behave the way we do but at the end of the day it always comes down to the self-centeredness of the heart. Love is the opposite of selfishness. Perhaps not the thing that passes as love these days but the love that God describes:
Love is kind and patient,
never jealous, boastful,
proud, or rude.
Love isn’t selfish
or quick tempered.
It doesn’t keep a record
of wrongs that others do.
6 Love rejoices in the truth,
but not in evil.
7 Love is always supportive,
8 Love never fails! (1 Corinthians 13:4-8, CEV)
Use whatever definition you want but this is the one that counts. This is the one that made a God who says he loves us, take action to show that love. This is the love that Jesus told us to have for God and for each other. A love that automatically puts the concerns of the other person ahead of our own and where sacrifice is a normal way of life. Imagine what the world would look like if this love permeated the hearts of everyone.
But it doesn't.
We were all born with a sinful nature that puts self ahead of everything and everyone else. As much as we try in ourselves to keep this love on the surface, what lay in the heart always rises up and dominates. This is why Jesus said the heart is key. It is the heart that will always dictate our actions, as hard as we try to work against it, because we know in ourselves what we want to be but we can't get there. Paul described the struggle of a religious heart without Christ:
I know that my selfish desires won’t let me do anything that is good. Even when I want to do right, I cannot. Instead of doing what I know is right, I do wrong. And so, if I don’t do what I know is right, I am no longer the one doing these evil things. The sin that lives in me is what does them. (Romans 7:18-20, CEV)
We must recognize that this all important love can only be produced in us supernaturally. If at any moment you think that you can do it without Jesus, you have stepped outside of the design of our Father and have taken your destiny into your own hands. It is an act of rebellion.
There is no good thing in us, everything having been tainted by that sin nature with which we were born. If we really want to live like Jesus and do what he did, there has to be a complete abandonment of everything and a bear hug on Jesus. It is only in the total surrender that we are able to be possessed and controlled by the Holy Spirit. Outside of that we are just playing games. Paul understood his condition and the only one who could save him:
With my whole heart I agree with the Law of God. But in every part of me I discover something fighting against my mind, and it makes me a prisoner of sin that controls everything I do. What a miserable person I am. Who will rescue me from this body that is doomed to die? Thank God! Jesus Christ will rescue me. (Romans 7:22-25, CEV)
If you really want to be a follower of Jesus; if you really want to do what he did; if you really want to have everything he promised; you have to give up everything else. You have to turn your back on everything you knew and surrender to the Father's embrace. What you were incapable to do he is capable to do through you. There is no other way. You have to decide between the world and the Kingdom; yourself and Jesus. By nature we are a sinful and self-centered people. By God's nature we are like Jesus. I end with this:
People who are ruled by their desires think only of themselves. Everyone who is ruled by the Holy Spirit thinks about spiritual things. (Romans 8:5, CEV)