Acts16:14 One of them was Lydia from Thyatira, a merchant of expensive purple cloth, who worshiped God. As she listened to us, the Lord opened her heart, and she accepted what Paul was saying. NLT
I have seen people that heard the gospel and didn't respond to the gospel. Their hearts were hardened and they didn't have a grasp of what was being said. In fact, this is the situation with every unsaved soul that has been hearing the gospel but has not responded. The reason alluded to this is that their hearts didn't open to what was being said. A veil seems to cover the eyes of their heart.
If you have an unsaved person in your family or neighbourhood that has not accepted Christ after hearing the gospel repeatedly, the heart of such a fellow hasn't been opened and you will need to intercede until that heart is totally opened. The bible made it clear that the devil has blinded the hearts of men so that they won't respond to the gospel(2Cor4:3-4).
When next you want to pray for that unsaved friend, family, neighbour, colleague and spouse, rebuke the spirit that has blinded his/her heart and command the veil covering his/her heart of understanding to fall off. Then pray God to send someone that will preach to him/her or better still, do the preaching if the person is within your reach.
Father, I command the demon spirit that has blinded the heart of...(Mention name) to come out and I decree that the veil covering the eyes of his/her heart fall-off by fire In Jesus Name.