Spiritual progress has no other test in the end, nor any better expression, than our ability to love. It has to be unselfish love founded on respect, a service, a disinterested affection that does not ask to be paid in return, a ‘sympathy’, indeed an ‘empathy’ that takes us out of ourselves enabling us to ‘feel with’ the other person and indeed to ‘feel in’ him or her. It gives us the ability to discover in the other person an inward nature as mysterious and deep as our own, but different and willed to be so by God.
In this fallen world the unity of human beings has been broken, everything is a ‘rat race’, and I try to free myself from the anguish that torments me by projecting it onto another, the scapegoat of my tragic finiteness. The other person is always my enemy and I need him to be so. In Christ, however, death has been defeated, my inner hell transformed into the Church, I no longer need to have enemies no one is separated from anyone. The criterion of the depth of one’s spiritual growth is therefore love for one’s enemies, in accordance with the paradoxical commandment of the Gospel that takes its meaning solely from the cross – Christ’s cross and ours – and from the resurrection – again Christ’s and our own.
(Oliver Clement, The Roots of Christian Mysticism, pp. 270-271)