Great love has the potential to open the heart space and then the mind space. Great suffering has the potential to open the mind space and then the heart space. Eventually both spaces need to be opened, and for such people, non-dual thinking can be the easiest.
People who have never loved or never suffered will normally try to control everything with an either-or attitude or all-or-nothing thinking. This closed system is all they are prepared for. The mentality that divides the world into “deserving and undeserving” has not yet experienced the absolute gratuity of grace or the undeserved character of mercy. This lack of in-depth God-experience leaves all of us judgmental, demanding, unforgiving, and weak in empathy and sympathy. Such people will remain inside the prison of “meritocracy,” where all has to be deserved. They are still counting when in reality God and grace exist outside of all accounting. Remember, however, to be patient with such people, even if you are the target of their judgment, because on some level, that is how they treat themselves as well.
Non-dual people will see things in their wholeness and call forth the same unity in others simply by being who they are. Wholeness (head, heart, and body all present, positive, and accounted for!) can see and call forth wholeness in others. This is why it is so pleasant to be around whole and holy people.
Dualistic or divided people, however, live in a split and fragmented world. They cannot accept or forgive certain parts of themselves. They cannot accept that God objectively dwells within them, as it states in so many places in Scripture, including 1 Corinthians 3:16-17. This lack of forgiveness takes the forms of a tortured mind, a closed heart, or an inability to live calmly and proudly inside ones own body. The fragmented mind sees parts, not wholes, in itself and others, and invariably it creates antagonism, reaction, fear, and resistance—“push-back” from other people—who themselves are longing for wholeness and holiness.
– Richard Rohr
Edge of Atlantic 