Clearly there are verses that say that an unsaved person cannot know or cannot understand the gospel. Some of the brethren seem to take these in an absolute sense. But, Paul's indictment of the pagans in Romans 1 is based upon the fact that, not only CAN they know the truth, they DO know it. Their knowledge is the basis for their condemnation. Consider this statment: Rom 1:18-20 For the wrath of God is revealed from heaven againsts all ungodliness and unrighteousness of men. who by their unrighteousness suppress the truth. For what can be known about God is plain to them, because God has shown it to them. For his invisible attributes, namely, his eternal power and divine nature, have been clearly perceived ever since the creation of the world in the things that have been made. So they are without excuse. How can it be argued that men CANNOT know or understand when it is so plain that they DO know and understand? Yea, what they already know and understand is the BASIS for their condemnation.