NOTES for Mat 6:1-15
The logic of the Sermon on the Mount continues here: the logic of interiorization, of moving spiritual life from the outside inward. True relationships with God do not consist in performing certain actions, but in the inner motivation for those actions. Best of all is when these actions become so inwardly natural to us that we ourselves no longer notice their motives. It is no accident that the words, "your Father, who sees in secret, will reward you openly," are repeated here like a refrain.
Almsgiving that is unnoticed from the outside, prayer without many words and without onlookers: these are elements of that naturalness. And Jesus Himself shows an example of such naturalness: the prayer "Our Father," born right here and now, which became the standard for Christians of every generation.
And it begins with the word most natural for the Son as He turns to the Father: "Abba," which would best be translated not as "Father" and not even as "Papa," but as "Daddy"; it is such a childlike and tender form of address.