Mike wrote: (1) "Manifest in them" means it has been made to be clearly seeable to them
(2) It is a matter of refusing the light that has been given.
Oh Mike; I usually avoid using the "A" word (Arminian) with you because you have rejected it in past.
BUT (1) I assume from this statement that you have been a converted Christian from the day you were born? Also that everybody all 7 billion of us are converted believers? Rom 1:18ff clearly identifies the reprobate unbeliever. You have vested too much power and knowledge in the sinner in his natural estate. Also Total Depravity being a Calvinist doctrine - you clearly advocate a lesser power in sin and a lesser power in the dominion of sin. That also is an Arminian concession to people power.
"But the natural man receiveth not the things of the Spirit of God: for they are foolishness unto him: neither can he know them, because they are spiritually discerned." 1Cor 2:14.
(2) This also is the Arminian doctrine of man-power. Man you are saying can reject his salvation! This God, This Christ and this Holy Spirit you proclaim are weak failures beaten by the average sinner. You have ditched sovereignty!! Does "Potter" and "clay" mean nothing but rhetoric??? in Scripture?
Mike; The first sentence of verse 18 is "For the wrath of God is revealed" How do you read that statement? And who is the wrath revealed too? The reprobate?
Also if you look at the sodomite accusations in v24-27 They have done that which is not natural. Not the natural way established and ordained by God. The sodomites know this is different but reject the way of God for the way of sin and lust.
This does not mean the Holy Spirit has "revealed" the truth to them, and failed. Similarly the church at Matt 7:21-23 who called Him "Lord, Lord..." and did things in His name, did not have the savingly revealed knowledge of faith. They were not called and not regenerated. Thus they were still of the flesh. "they that are after the flesh do mind the things of the flesh" "to be carnally minded is death" Rom 8:5,6.
These reprobates "know" of God because the church has witnessed to society and the Bible is in plain sight for all to see. But this "knowing" is like Satan's knowing - even the devils accept God but are not saved. The thief knows he is breaking the law because he has a conscience which tells him the difference between right and wrong. But that is not saving knowledge.
Finally God reveals Himself. But sin has power and dominion over the natural estate.