Thematic Bible: The last enemy that shall be destroyed

Therefore, since the children share in flesh and blood, he likewise shared in their humanity, so that through death he could destroy the one who holds the power of death (that is, the devil), and set free those who were held in slavery all their lives by their fear of death.

For he must reign until he has put all his enemies under his feet. The last enemy to be eliminated is death. For he has put everything in subjection under his feet. But when it says "everything" has been put in subjection, it is clear that this does not include the one who put everything in subjection to him. read more.
And when all things are subjected to him, then the Son himself will be subjected to the one who subjected everything to him, so that God may be all in all.