2 Corinthians 4:4(English Standard Version)
4In their case the god of this world has blinded the minds of the unbelievers, to keep them from seeing the light of the gospel of the glory of Christ, who is the image of God.
We live in a culture and a world today that has been blinded to the truth of God, and especially of Jesus Christ. There are many out there that refuse to hear the truth, that will not speak the name of Jesus if they can help it, and that cannot see how Jesus works though the lives of those who know Him. No matter how rational and sound your arguements for the truth, they are determined to refuse to hear, speak or see it.
The apostle Paul had much the same problem with people of his day. As the good news of Jesus Christ was bringing many to this new faith, there were many that refused to hear, speak or see in much the same way as is done. The reason for this is that the god of this world, Satan, blinds those that are lost to the truths of God. Many would rather believe lies than to admit their sin and yield to the grace and mercy of Jesus Christ. Unfortunately we all know people that we encounter in our lives that have this problem.
What should we do? Our job is to continue to be witnesses to what God has done in our lives. We need to take the time to listen to their questions and doubts and hear why they believe as they do. We should then speak the truth in love, relaying our testimony of how Jesus has worked in our lives. Finally we need to not be blinded to those around us who are perishing; we need to see each and every person as one who is loved passionately by God, no matter how difficult they may be.
Everyone needs to know about Jesus Christ and what He has done for them; everyone needs to be given the opportunity to be saved as we have been. It is our responsibilty that they are shown the "light of the gospel".