Reprobation is the name given to God’s eternal decision regarding those sinners whom he has not chosen for life. His decision is in essence a decision not to change them, as the elect are destined to be changed, but to leave them to sin as in their hearts they already want to do, and finally to judge them as they deserve for what they have done. When in particular instances God gives them over to their sins (i.e., removes restraints on their doing the disobedient things they desire), this is itself the beginning of judgment. It is called “hardening” (Rom. 9:18; 11:25; cf. Ps. 81:12; Rom. 1:24, 26, 28), and it inevitably leads to greater guilt.
Reprobation is a biblical reality (Rom. 9:14-24; 1 Pet. 2:8), but not one that bears directly on Christian behavior. The reprobates are faceless so far as Christians are concerned, and it is not for us to try to identify them. Rather, we should live in light of the certainty that anyone may be saved if he or she will but repent and put faith in Christ.
We should view all persons that we meet as possibly being numbered among the elect.
--JI Packer, read the whole article here
