Proverbs 28:5 Evil men understand not judgment: but they that seek the Lord understand all things.
Unbelieving sinners do not understand (because they do not believe God’s Word) the justice and judgment of the Law upon themselves, nor do they understand the just judgment of the Gospel upon our sin in Christ. On the other hand, God promises that believers in Christ, “they that seek the Lord,” understand all things.
That’s an incredible promise that is hard to believe on the face of it, but we understand the promise to include all the things necessary for life and salvation. “All things” means all spiritual things. This is what faith does: it gives sight, spiritual understanding, to see the truths and promises of God. “Faith is the evidence of things not seen.” “Blessed are those who have not seen (physically) and yet have believed.”
We who believe in Jesus understand all things. We understand that we are sinners and that Jesus died for sinners to forgive them and to give life to whoever believes. This we understand by the teaching of the Spirit through the Gospel. We understand all things necessary, for we have the “one thing needful.” Without conversion the human sinner is spiritually blind, dead inside, and opposed to God. After conversion, the logical necessity of Christ makes sense: we see, we are born again, and we are reconciled to God forever.