Morality comes from loving The Truth.
If you love The Truth, you will come to realize that you are wrong, even when you were sincerely believing to be right.
Having this real humility that comes from a realization of one's own faultiness, we forgive others for their faults, for if we condemn them, we really condemn ourselves for being no better.
Morality comes from love of The Truth. Truth is the standard.
That is why Jesus says that loving your neighbor as yourself is a commandment like unto loving God with all your heart, soul, and mind.