Paul's Statement That No One Understands

In Matthew 13, 13, Jesus recites a prophecy from the book of Isaiah foretelling Israel's inability to grasp the gospel. And so if what Jesus says here is true, that only those who understand the gospel will bear fruit and prove themselves to be truly born again, then how are we to deal with Paul's statement that say that none understand? We have a theological dilemma here, right? That if Jesus says that we have to understand, yet Paul says that none understand. Are Paul and Jesus at odds with one another? Is somebody lying or wrong in this passage of scripture? Of course not, right? The logical conclusion is that those who do understand only understand because they have been