In Romans 1:18-23 Paul says that God has revealed Himself in men’s conscience and God has also revealed Himself in creation. Men may not have had every piece of information about God but they were able to know that He existed and had seen evidence of His power. They did not follow what Light they had, turning to idolatry and violating basic moral codes, thus they are guilty. Without mentioning Adam, original sin, or the Covenant, Paul has given an irrefutable argument that no one, regardless of geography, regardless of era, is guiltless A man who has never heard of Jesus or the Bible is still guilty before a holy God.
In Romans 1:19-20 Paul asserted that men everywhere had ample evidence of a Creator both in their conscience and in viewing the created world. Men decided to ignore the moral code imbedded in their conscience. They engaged in all sorts of unrighteous living even though they knew it was wrong. They also made a conscious decision to ignore the Creator and worship the creation.
All men today are also without excuse. I observe people all around me, lost and saved, in church and out of church, and I see the exact same thing Paul saw. What is even sadder still, I look at myself and I see much the same thing at various times. Praise God that His revelation does not end with this bad news. Praise God that Romans 5:8 follows, otherwise all of us would be “without excuse”. Romans 5:8 says, “But God demonstrates His own love toward us, in that while we were yet sinners, Christ died for us.” NASU
Jesus said in John 15:22 says, "If I had not come and spoken to them, they would not have sin, but now they have no excuse for their sin.” NASU The word “excuse” is found in most English translations only three times in the New Testament. Two are translated from the same Greek word in Romans 1:20 and 2:1. The third place is here in John 15:22 but the original Greek word is not the same. The KJV renders it “cloke” (sp), while the NKJV uses “excuse”. I believe that the KJV is closest. We really do not have an “excuse” for our sin now. What we have is a “cloak” or “covering” for our sin. Christ, our cloak, doesn’t just cover our sin, He takes away our sin.