I studied biology/pre-med in college, and, as with any major, some courses were more challenging than others. Then there were other classes that were what you might call "filtering" classes. I remember talking to one of my hockey teammates about taking organic chemistry, and he remarked; "That's the class they use to weed you all out, huh?" He was spot on. At the start of the year, the lecture hall was full. By the end of the year, over half of the seats were empty. It was a class that tended to filter out those who would go on to finish their science degree, and those who wouldn't. If you could make it through o-chem, chances are you'd graduate (even if some of the later classes were more difficult). I think the back half of Romans 1 is one of those kinds of texts in Scripture. It will tend to filter people; between those who will hold to the authority of Scripture and believe what God says, and those who won't. I think that's one of the purposes of difficult passages in Scripture, and part of the work of God's word. It provokes people to make a decision; either believe or do not; accept or reject. It might be easy to build a church and draw a crowd saying wonderful and pleasing things. But the test will come when we must teach what is not popular (and what is popular will change with culture and time). We see this in Jesus' own ministry at the end of John 6, as Jesus teaches difficult things and many walk away. He then challenges the disciples, seeing if they too will reject His word. This is why Jesus taught in parables, so that there would be a clear delineation between those who would receive His teaching, and those who wouldn't (see Luke 8:9-10). This is part of the work of God's Word (including passages like Romans 1), to be a dividing line between those who will believe and those who will not.