‘But he that is spiritual judges [discerns] all things’ – things in the Bible, that is – ‘yet he himself is judged [discerned, understood] of [by] no man.’ Of course he isn’t, because a person who doesn't know the mind of the Lord, doesn't understand a Christian.
How can Christians and non-Christians work together in the gospel? How can Bible-believing churches work hand in hand with churches that reject the fundamental truths of Scripture? They have nothing in common. The liberals cannot grasp the thinking of evangelicals. They are heading in different directions, and it is disobedience and wilful ignorance of what Paul says here to even try to cooperate together. Christians are left in this lost world to try to win it for Christ, not to behave as if churches composed of natural men and women are capable of understanding or contributing to the work.
Do believers really have the mind of Christ? We are not said to have the mind of Christ in the sense that we have got the infinite mind of God; of course not. You have the mind of Christ in the sense that you have his truth, his teaching. You love the same things that he loves, and hate the things he hates. We have a true understanding, though at a far greater level. What a privilege! You and I have the will of the eternal Son of God grafted into us in our understanding.