Other comments on this day's readings can be found here.
Reading 1 - 2Samuel 22:26
"To the faithful you show yourself faithful, to the blameless you show yourself blameless" (2Sa 22:26).
This principle is developed in the Lord's prayer: "For if ye forgive men their trespasses, your heavenly Father will also forgive you: but if ye forgive not men their trespasses, neither will your Father forgive your trespasses" (Mat 6:14,15; cp also Mat 18:33-35; Jam 2:13). And, conversely, God's ways do not appear right to those who themselves are not upright: cp Mat 25:24; 27:5.
Reading 2 - Jeremiah 25
In Jer 25, Jeremiah predicts vengeance upon the Philistines in the Last Days. He lists their cities (v 20) along with "all the mingled people" (vv 20,24 -- the word is "ereb", closely related to "Arab") of Egypt, Edom, Moab, Ammon, Tyre, Sidon, Dedan, Tema, Arabia, Elam, and Media -- all Muslim territories -- and finally Babylon. God will cause all of these to drink of "the wine cup of this fury" (v 15). This figure of a "cup" of judgment being filled up to the brim, and given by God to the wicked, is common in the Bible, and is often used in regard to the great judgments of the Last Days (Psa 11:6; 75:8; Isa 51:17,22,23; Oba 1:16; and esp Rev 14:8,10; 16:19; 18:6).
Reading 3 - Romans 13:3
"For rulers hold no terror for those who do right, but for those who do wrong. Do you want to be free from fear of the one in authority? Then do what is right and he will commend you" (Rom 13:3).
This seems to take no account of the possibility that government may be tyrannical and may reward evil and suppress good. A few years after Paul wrote these words, Nero launched a persecution against the believers at Rome; multitudes lost their lives, and not because of doing evil. Later on, other emperors would lash out against Christians in several waves of persecution stretching over more than two centuries.
One way to deal with the problem is to assume that Paul is presenting the norm, that is to say, the state as functioning in terms of fulfilling the ideal for government, which is certainly that of punishing evil and rewarding or encouraging good.
Another, and better, possibility: consider the principle of Rom 8:28, whereby God finds ways to bring good out of apparent evil, so that even in the event that the state should turn against the people of God and persecute them cruelly and unjustly (as in 1Pe 3:12-17), God will bring good out of that evil too, in the long run. Sometimes God may speak more clearly out of prison cells and graves than out of the lives of believers who live securely and at peace with their rulers!
AND HE WILL COMMEND YOU: Possibly the "he" here could refer to God -- who is, after all, the ultimate ruler and authority in any case!