My wife and I have a child that we want to grow to be a faithful member in the Lord's church. His grandparents were once in the Lord's church but left and now attend a Pentecostal church. Is it wrong for us to keep him from his grandparents because of their religious beliefs?
"I have given them Your word; and the world has hated them, because they are not of the world, even as I am not of the world. I do not ask You to take them out of the world, but to keep them from the evil one. They are not of the world, even as I am not of the world" (John 17:14-16).
Complete isolation does not produce strong Christians. While you would want to limit your time with your parents because they are no longer faithful Christians, you still have duties as a child of theirs to make sure they cared for as they get older. Just explain to your child that his grandparents do not hold the same religious beliefs as his parents. Teach him what is wrong about Pentecostalism. Let him visit his grandparents, if that is desirable, but always make sure that he attends worship and Bible study at a true church.