"For if you forgive other people when they sin against you, your heavenly Father will also forgive you. But if you do not forgive others their sins, your Father will not forgive your sins." Matthew 6:14-15
According to Jesus and the Letter to the Hebrews, the New Testament (Covenant) begins with the blood of Jesus not his birth (Matthew 26:26-29; Luke 22:19-20; Hebrews 9:16-28).
Matthew 6:14-15 are the earthly, pre-cross words of Jesus under the old covenant of law where forgiveness is conditional and requires perfection (70x7-Matthew 18:21-22).