In Heaven, both in the intermediate state and on the New Earth, we will know each other, including those we knew on earth. Here’s some evidence:
1. Heaven will not reduce our mental capacities, but sharpen them (1 Cor. 13:12). We will not be dumber in heaven, but smarter. Scripture gives no indication of a “memory wipe” that will cause us not to recognize our loved ones and others we’ve known. If we wouldn’t know our loved ones, the consolation of afterlife reunion in 1 Thes. 4:14-18 would be nonexistent.
2. After his resurrection, Jesus was not recognized at first on a few occasions (John 20:15; Luke 24:15-16), suggesting some change in appearance. After being with him awhile, his disciples suddenly recognized him (John 20:16; Luke 24:31). This suggests that despite any outer appearance change, the inner identity of the person may shine through, especially to eyes enlightened by heaven.
3. In Matt. 17:1-4, at the transfiguration, Moses and Elijah were recognized by the disciples, even though they weren’t told who they were, and they couldn’t have previously known what they looked like. This may suggest we could recognize instantly people we know of but have not previously met, perhaps as a result of individual personality emanating through their physical appearance.
4. Even apart from the direct indications of Scripture cited above and below, it would logically follow that we would know our loved ones in heaven. We will know some we didn’t know on earth—but surely we will still know all those we did! We don’t lose knowledge in heaven—we gain it! The nature of love itself is abiding in a way that transcends death (1 Cor. 13:13). While we will no doubt lose interest in and choose not to recall many things that attracted us on earth, the shared experience of loving relationships forges a camaraderie parallel to that of soldiers who have served together in the trenches, and who never forget what they experienced together in that foreign land called earth.
For more information on the subject of Heaven, see Randy Alcorn’s book Heaven.