For you had compassion on those in prison, and you joyfully accepted the plundering of your property, since you knew that you yourselves had a better possession and an abiding one.
So Hebrews 10:34 is saying that the key to the indomitable joy that releases love and good works and that embraces suffering with those who suffer is knowing that you have this better and abiding possession. “Knowing!” Here’s the key! You must have this confidence. It’s this deep confidence about your future that frees you from the fear and greed that kill love and make you into a cookie-cutter human who has to have security and safety and ease and comfort.
So where does that “knowing” come from? That confidence? The answer to that is what this whole book is written to supply. Our confidence comes from Christ – what he did perfectly on the cross and at the resurrection, what he is doing now for us in heaven and what he will do for us at the second coming and to all eternity. Christ is the one who destroyed the power of death (2:15). Christ is the High Priest who opens the way to the throne of grace (4:15-16). Christ is the one who ever lives to make intercession for us (7:25). Christ is the one whose blood cleanses our consciences (9:14), and obtained an eternal redemption (9:12). Christ’s death is the single sacrifice that perfects us for all time (10:14). Christ will make all his enemies a footstool for his feet (10:13). Christ will come again a second time to save all who are eagerly waiting for him. Christ is the mediator of a new and better covenant that insures the forgiveness of our sins, and the writing of the law on our hearts, and the presence of God in our midst forever and ever (8:6-11).
All that we ever hope for is owing to Christ. We receive it not by earning it or meriting it, but by banking on it. If we love it above all that earth offers, it is ours. So when verse 34 says that the key to indomitable joy in the face of suffering and earthly loss is “knowing that we have a better possession and an abiding one,” it means that we know this because of Christ. Christ is the seal and the guarantee of our hope in all the promises of God.