“Paul describes this faith in most significant words, namely, when we cry Abba! Father! For in the spirit of fear it is not possible to cry, for we can scarcely open our mouth or mumble. But faith expands the heart, the emotions, and the voice, but fear tightens up all these things and restricts them, as our own experience amply testifies.
Fear does not say Abba, but rather it hates and flees from the Father as from an enemy and mutters against Him as a tyrant. For those people who are in the spirit of fear and not in the spirit of adoption do not taste how sweet the Lord is (cf. Ps. 34:8; 1 Peter 2:3), but rather He appears to them as harsh and hard, and in their heart they call Him a virtual tyrant, although with their mouth they call Him Father, just as that slave in the Gospel who when he had hidden his master’s money said to him: ‘Master, I knew you to be a hard man, reaping where you did not sow, etc.’ (Matt. 25:24).
Such are the people who are displeased that God accepts no man’s merits but has free mercy. Thus they say: ‘Thou has commanded the impossible, Thou hast not given grace but only knowledge; this I still have, and I give it back to you.’
Rather they ought to rejoice because He has not put our hope in ourselves but only in Himself, in His mercy. All who are of this mind are secretly saying in their hearts: ‘God acts in a tyrannical manner, He is not a Father, but an enemy,’ which is also true.
But they do not know that one must agree with this enemy and that thus, and only thus, He becomes a friend and a Father. For He will not come around to our way of thinking and be changed for us, so that we may become His friends and sons.”
–Martin Luther, Luther’s Works: Lectures on Romans, Volume 25 (St. Louis: Concordia, 1972), 358-359. Luther is commenting on Romans 8:15-16.
[HT: Mark Dever]