Why will God not forgive us, if we do not forgive others?

We are called to imitate God and may expect that God will treat us as we have treated his living icons, even “the least of these my brethren” (Mat 25:40; Heb 2:11; see Q578b). As the Lord teaches:

Love your enemies, and pray for those who persecute you, so that you may be sons of your Father who is in heaven; for he makes his sun rise on the evil and on the good… You therefore must be perfect, as your heavenly Father is perfect. (Mat 5:43–48)