And they shall see his face; and his name shall be in their foreheads.
See his face - revealed in divine glory in Christ Jesus. They shall know Him with intuitive knowledge, even as they are known by Him (1 Corinthians 13:9-12): face to face. Compare 1 Timothy 6:16, with John 14:9. God the Father can nobly be seen in Christ.
In - `on their foreheads.' Not only shall they personally, in secret (Revelation 3:17), know their sonship, but shall be known as sons of God to all citizens of new Jerusalem; so that the free flow of mutual love among Christ's family members will not be checked by suspicion, as here.