Read 1 Corinthians 2.
In this chapter, Paul explained to the Corinthians his approach to ministry. That approach was to rely on the message of Christ (v. 2) and the power of God’s Spirit (v. 4).
Verses 14-15 described the differences between those who have God’s Holy Spirit and those who do not. Unbelievers―those who don’t have the Spirit―cannot welcome God’s truth because God’s truth is spiritual by nature.
Sometimes verse 14 is interpreted to mean that unbelievers cannot understand God’s word. That is not the point of the passage, however. The point of the passage is that an unbeliever is unable to believe, to welcome, to “accept the things that come from the Spirit of God” (v. 14).
Unbelievers may understand every fact of the Gospel or every doctrine of the Christian faith or they may not, but either way an unbeliever can only believe God’s truth if God’s Spirit is within.
This is why our outreach to unbelievers should consist of the pure gospel of Christ rather than persuasive techniques, convincing arguments, or powerful entertainment. Those might bring some genuine conversions–if there is any gospel at all in them–but they will also bring many false professions.
Only the Holy Spirit’s power can change a person’s will so that that person will welcome Jesus Christ and put his or her faith in him. So stick to the gospel message and pray for God to save through his Spirit.
That is the righteous approach to evangelism.