18 For the wrath of God is revealed from heaven against all ungodliness and unrighteousness of men who suppress the truth in unrighteousness, 19 because that which is known about God is evident within them; for God made it evident to them. 20 For since the creation of the world His invisible attributes, His eternal power and divine nature, have been clearly seen, being understood through what has been made, so that they are without excuse. 21 For even though they knew God, they did not honor Him as God or give thanks, but they became futile in their speculations, and their foolish heart was darkened. 22 Professing to be wise, they became fools, 23 and exchanged the glory of the incorruptible God for an image in the form of corruptible man and of birds and four-footed animals and crawling creatures.(Romans 1)
Here we can see how far natural revelation takes someone in remote areas who have never heard the gospel my friend. They can see God through it. Many people in these areas have a god they worship, such as a sun god for instance. But this sun god is not God, and this is no sign they are saved. It is proof they are pagan idol worshippers. They take that which they see and take God’s glory and give it to idols. That is the thrust of Paul’s argument here.