First, let's consider what Louis Berkhof has to say about "inability" (emphasis mine):
"Here again, it is necessary to distinguish. Reformed theologians generally maintain that the sinner is still able to perform (a) natural good; (b) civil good or civil righteousness; and (c) externally religious good. He may perform acts and manifest sentiments that deserve the sincere approval and gratitude of their fellow-men, and that even meet in a measure with the approval of God. Yet when these words are considered in relation to God, they are radically defective, since they are not prompted by love to God, nor by any regard for the will of God as requiring them. Moreover, man cannot change his fundamental preference for sin to love for God, nor even make an approach to such a change. There is abundant Scriptural support for this doctrine, John 1:13; 3:5; 6:44; 8:34; 15:4, 5; Rom. 7:18, 24; 8:7, 8; I Cor. 2:14; II Cor. 3:5; Eph. 2:1, 8-10; Heb. 11:6."
It is VERY important to understand what Berkhof is saying here because we see it and experience it daily. It is this, God's common grace working through unregenerate people for the blessing and benefit of mankind (believing and unbelieving).
It's very likely that you have a relative, neighbor, or friend who regularly exercises various acts of kindness or extends generosity to you and your family. Because man looks on the outside, we may be tempted to consider that person to be a believer--based only on select actions/behavior--though he/she gives no evidence of saving faith (i.e. affections for God and His people, desire to know and please God, desire to worship God, etc.).
As Christians, we need much wisdom and discernment as we live among people who are on the path to destruction. May God grant us such wisdom and discernment so that the "works" of man may become works "unto God" for His glory and His purposes!
