There is a grief that is biblical (1 Thess. 4:13), but it is different from that of the unbeliever. Why?
Well, first of all the believer who died has gained by his death (2 Cor 5), because he is now with Christ which is far better. Those believers he leaves behind grieve (he doesn’t), because they “lose” him. Grief has solely to do with those remaining behind—so they are sorry for themselves—that they no longer have his presence with them. But, unlike unbelievers, they know where he is and rejoice for him. At death (among believers), then, there is both gain and loss. Among unbelievers there is nothing but loss– for both the dying and for those left behind. There is no gain for anyone. What a difference!
Moreover, for the believer and his believing dead loved one, there is nothing permanent about the loss; he will be with his loved one once more when he goes to be with the Lord.
So the fundamental difference has to do with gain and loss—but what a difference it is!