Jesus considers the first commandment as the most important and He considers the next as a very close second. I think if we have any theology at all, that no one has difficulty with the first. But, why should we love others as ourselves? The answer is vital within my concept of, and our relationship to, God.
Have you ever asked yourself: "What's in it for God?" "Why should God care about us?" "Are we a game or plaything or something He's devised for His own amusement?" "What's this about our being in the image of God? Does that mean we look like Him?" "And what's this bit about Heaven? Are we really going to float around on clouds or walk around on golden streets and live in mansions?" "What sort of grandiose ego does humankind have that it considers itself of any concern to some Supreme Being; that It is simply there for our own betterment promising eternal life provided we try to be good or even if we say we're sorry for being bad?" .............Consider with me an alternative...
I believe that God is evolving constantly as the Good within the spiritual universe. I believe that our soul is potentially a portion of God's Spiritual Being. This is how I put it in my 1998 Lenten Reflection:
"Every person has control of their own good and evil spiritual mix.
While God is quite aware of evil, it is not a component of God's own evolution of which the development of our individual soul is an important however small a contributing part.
To the extent we are spiritually able to exclude evil, the presence of God can be more manifest within us.
I believe that in Jesus, to secure the transition to a New Testament of love and compassion, God was able to intervene to the complete exclusion of evil and thus to become fully manifest spiritually within the soul of Jesus. I believe His soul, thus fulfilled, continues within God and as such, Jesus may be referred to as the Son of God.
He is a part of God; as are we all, to the extent of our spiritual goodness which constitutes the immortal portion of our soul.
It is the contribution of the spiritual goodness within our collective immortal souls throughout the universe that enhances God's continuing evolution.
This accounts for the Lord's vital interest in our seeking to maintain and strengthen our spiritual goodness which eventually becomes a part of Him to constitute our immortality."
So, if God has this synergistic relationship with us and the goodness of our souls is potentially a part of God, then in effect our failure to love others as ourselves is personally offensive to God. Simply put we are all in this together for God's own purpose of which we are a small but important part. Let's respect that and rejoice in it.
Jesus' allegorical reference to the duality of the soul and the part that's taken.