Romans 1:28: And even as they did not like to retain God in their knowledge, God gave them over to a reprobate mind, to do those things which are not convenient;
Reprobate is a frightening word. Albert Barnes NT Commentary:
To retain God means to think of him, or to serve and adore him. Not thinking of Him, serving Him and adoring Him was the first step in their sin. It was not that God compelled them; or that he did not give them knowledge; nor even is it said that he arbitrarily abandoned them as the first step; but they forsook him, and as a consequence he gave them up to a reprobate mind.
Thinking properly about God leads unfailingly to serving Him and adoring Him. Individuals are in a desperate condition who have been described By God as reprobate. Reprobate definitions: Unapproved, rejected; by implication worthless (literally or morally), castaway.
There are all sorts of sins that we consider worse than not thinking properly about God. Murder, lying, stealing, adultery etc. come to mind. But God can forgive all of those. It is a worse offense not to think of Him properly. He gave those who continued to offend in that way over to a reprobate mind.
2 Timothy 3:8: Now as Jannes and Jambres withstood Moses, so do these also resist the truth: men of corrupt minds, reprobate concerning the faith.
John 17:17: Sanctify them through thy truth: thy word is truth.
Those who continually resist truth from God (the Bible) have reprobate minds, unable to think properly about God.
Titus 1:16: They profess that they know God; but in works they deny him, being abominable, and disobedient, and unto every good work reprobate.
Those with reprobate minds deny Him and stubbornly refuse His influence in their lives.
2 Corinthians 13:5: Examine yourselves, whether ye be in the faith; prove your own selves. Know ye not your own selves, how that Jesus Christ is in you, except ye be reprobates?
The only choices men have are to receive Jesus into their hearts or become reprobate.
Ezekiel 3:18-19: When I say unto the wicked, Thou shalt surely die; and thou givest him not warning, nor speakest to warn the wicked from his wicked way, to save his life; the same wicked man shall die in his iniquity; but his blood will I require at thine hand. 19 Yet if thou warn the wicked, and he turn not from his wickedness, nor from his wicked way, he shall die in his iniquity; but thou hast delivered thy soul.
Jude 1:22-23: And of some have compassion, making a difference: 23 And others save with fear, pulling them out of the fire; hating even the garment spotted by the flesh.
Mark 6:34: And Jesus, when he came out, saw much people, and was moved with compassion toward them, because they were as sheep not having a shepherd: and he began to teach them many things.
Dr. J. Vernon McGee said that when we communicate about judgment, Hell and the Lake of Fire we should do so with tears over the lost condition of others. We should have compassion on them as the Bible commands and as Jesus did. If we do not reprove them of sin and do not share the gospel with them, (or at least pray for them and support ministries that do) God will hold us accountable.