But we do not want you to be uninformed, brothers, about those who are asleep, that you may not grieve as others do who have no hope. For since we believe that Jesus died and rose again, even so, through Jesus, God will bring with him those who have fallen asleep.
1 Thess 4:13-14
Our hope of seeing loved ones who have died is predicated on the knowledge of Jesus' resurrection: our hope of resurrection is based on our belief that Jesus died and rose again. Or, in other words, when a fellow christian dies we view it as a temporary separation because that's what happened with Jesus....
It is clear, however, in the wording "even so, through Jesus" that it is only through identification with Jesus that this will happen. There is no hope of resurrection apart from Jesus - he is not merely the proof (or example) that resurrection is possible - he is the author (ie. the basis) of the resurrection.
(The temporary nature of grief and suffering is underlined in Rev 21:4, which declares that the day will come when "death shall be no more, neither shall there be mourning nor crying nor pain anymore")