Which shows conscience is essential, if it is not defiled, for it is a sound conscience which God uses to guide those without His word, and to convict them of violating what is right, and thus for their need for the Savior. If those in Rm 1 had obeyed the light they had via conscience they would have come to the Light, even Christ. Thus the problem is a defiled conscience.
For when the Gentiles, which have not the law, do by nature the things contained in the law, these, having not the law, are a law unto themselves: Which shew the work of the law written in their hearts, their conscience also bearing witness, and their thoughts the mean while accusing or else excusing one another;) (Romans 2:14-15)
But when ye sin so against the brethren, and wound their weak conscience, ye sin against Christ. Wherefore, if meat make my brother to offend, I will eat no flesh while the world standeth, lest I make my brother to offend. (1 Corinthians 8:12-13)
And herein do I exercise myself, to have always a conscience void of offence toward God, and toward men. (Acts 24:16)
And they which heard it, being convicted by their own conscience, went out one by one, beginning at the eldest, even unto the last: and Jesus was left alone, and the woman standing in the midst. (John 8:9)
Holding faith, and a good conscience; which some having put away concerning faith have made shipwreck: (1 Timothy 1:19)
I agree.