Spiritually discerned

“The man without the Spirit does not acept the things that come from the Spirit of God, for they are foolishness to him, and he cannot understand them, because they are spiritually discerned.” 1 Corinthians 2:14
There are many Biblical doctrines that make no sense to a non-Christian – for example: the Trinity, God becoming man and dying, the indwelling of God’s Spirit, loving people you don’t like, the notion of turning the other cheek and putting others first, humility being better than pride, the last being first and the first being last. Yet we know them all to be true.
These things are foolishness to the world. With the natural mind, we cannot figure them out. But by God’s Spirit, these truths are revealed to us as believers. Even the Scriptures hold no power for the non-Christian reading them; they are just a bunch of words on pages. But when we are born again, and we have the Author Himself indwelling and guiding us, those very same words become alive.
This is why there is very little that can be gained from discussing these kinds of doctrines with unbelievers – be they at your workplace, or knocking at your door. Cut to the chase and present the gospel to them: all have sinned and fallen short of the glory of God, Jesus Christ came to save sinners such as we through His death on the cross and His resurrection three days later, we can be forgiven of our sin and receive God’s free gift of salvation if we repent from and confess our sin, and believe on Him for eternal life. The other things can wait, until after they are saved, when they will have the understanding that only comes through the Holy Spirit.