Verse 3 says that if our gospel be hid, it is hid to them that are lost, to those who have not accepted the truth of God's word. The reason they have not accepted it is because Satan, the god of this world has them blinded to the good news of the gospel. He doesn't want anyone to be saved. He'd rather drag them down to hell, to a lost eternity. He doesn't want the light of the gospel to penetrate the darkness that he has them kept in bondage in.
But, we must continue to preach. And when you preach, be sure, very sure you preach Christ Jesus and not about yourself. It is so important that we tell all we come in contact with that Jesus Christ died so that they could have eternal life. Tell them that they don't have to live in darkness and despair. Tell them they can have the light of the world, who is Jesus Christ and when they receive Him, all their darkness will have to go. No darkness or despair can exist when Jesus is present.