Question: "What is reprobation? What does it mean to be reprobate?"
Answer: “Reprobation” is the term used to describe those who by default are left in their fallen human nature to sin and to be eternally damned. It can be the only possible consequence if, as Scripture declares, God has foreknown and chosen others to eternal life through His only begotten Son, the Lord Jesus Christ (Ephesians 1:4-5; Romans 9:24-25). In Acts 13:48, we read, “And all who were appointed for eternal life believed.” From this, we see that the decree of reprobation is a result of unbelief or, rather, the decree of reprobation results in unbelief. Some theologians declare from Scripture that God foreknew some and reprobated others, prior to the Fall of Adam. This is called supralapsarianism, from the Latinsupra meaning “above” and lapsus, meaning “fall.” Others maintain that foreknowledge and reprobation were decreed to happen as a consequence of the Fall, and this is termed “infralapsarianism.”
The existence of the state of reprobation can be deduced from the Scriptures in many places, such as Proverbs 16:4 and Jeremiah 6:30, just to name two. Although it describes the fact that God has rejected some, there is a sense in which those whom He has rejected still serve His purposes, despite their willful rebellion. The best example is the raising up of Pharaoh in the book of Exodus. Here was a man who clearly refused to obey God, despite Moses’ repeated petitions to let the Israelites leave the land of Egypt. But the thing we note about Pharaoh is that, despite his willful obstinacy, God was nevertheless glorified through him. Reading Exodus 9:13-16, we note that God says He could have wiped the whole of Egypt and Pharaoh out of existence were it not for His wish to demonstrate His power and make His name known throughout the earth (Exodus 14:4,31). Clearly, God will fulfill all of His eternal purposes, both through those whom He has foreknown (Philippians 2:13) and through those whom He has rejected—the reprobate (Romans 9:22). In both cases, God will receive the highest honor and glory.
Finally, the question that remains is whether we can declare anyone to be reprobate in this life. Clearly, we cannot. The doctrines of grace as purported by John Calvin are both the hub and very essence of reformed theology, but sadly some have taken them to the extreme. Hypercalvinism, for example, dares to declare that the taking of the gospel to the world is unnecessary if God has already decreed those He would or wouldn’t save. However, John 3:16 would not say “For God so loved the world that He sent His only begotten Son that whoever believes in Him should not perish but have everlasting life” if, indeed, we were privy to such secret things as those who are reprobate. Our responsibility is to preach the gospel to all men everywhere, pleading with them to be reconciled to God (2 Corinthians 5:20).