Why should we be patient with people who do not understand the gospel?
We should be patient because the natural, unregenerated man cannot receive or understand the things of the Spirit; they are foolishness to him and are spiritually discerned. Since only God can open eyes and hearts, we wait on His timing, even if it takes years.
Les explains from 1 Corinthians 2:13-14 that Paul makes this plain: the natural, unconverted, unregenerated, unsaved, lost man receives not the things of the Spirit of God, for they are foolishness unto him. He cannot understand or know them because they are spiritually discerned. Therefore, Les says we have to be real patient with unbelievers, even if it takes three years for them to come to understanding of the gospel. He is patient because he realizes they cannot comprehend these things until God opens their eyes and hearts, and we leave that to His own good timing.