Isaiah is an evangelist, a cross-preacher.
The Cross as Invite to the Wedding Supper for the Whore - v6.
Isaiah pictures a mountain feast to which all peoples are invited by The LORD of Hosts. Isaiah elsewhere says The LORD of Hosts is our Maker and our Husband. This is invitation to the Wedding Supper of Heaven's Son. Christ as the Feast-Maker who invites us to feast with him and upon him - pictured in every meal we eat. Is this a invite to a friend to come to a wedding? No it's the invitation of The Faithful City who has become a Whore (Isaiah 1:21a). And that's only possible by The Feast-Maker dying for her whoredom, the faithful one bearing the cost of all her unfaithfulness. The Feast-Maker is crushed and afflicted, his invitation to feast is written in his own blood.
The Cross as Death's Swallowing up by its Swallowing of Christ followed by Resurrection - v7-8.
Isaiah tells us of a future in which death is finished. The great enemy that we try to escape, try to redefine, try to ignore... but which swallows up everyone.... it got its dirty mits on the perfect son of heaven. Death swallowed Jesus. But Jesus was not caught off guard, he came and set his face to the cross. Death exists because he would have to die. Our sinful Adamic flesh isn't reformable, it can't just be won over to something better. This dead man walking needs to be put to death - and Jesus offers life not by avoiding death, but life on the other side of judgement. Death swallowed up Jesus and then he swallowed up death in resurrection - he takes us into death with him, and will bring us through to resurrection as sure as a thread follows its needle.
The Cross as The Exchange that gives us The Crucified Christ - v9.
Finally, Isaiah's vision of the future tells of a lifted veil and a glorious moment of seeing. The story ends face to face. We spend our dies hiding from one another and from god, living with masks not with reality and yet longing for real intimacy. We were made to know and be known. The Wedding Jesus invites us to is one in which he makes his vows - all that I have I share with you. He takes all that is ours on hiimself, and gives all that he has to us. Chiefly, he gives us himself. This covenant costs blood - his blood. I am his and he is mine - bought with the precious blood of Christ. I have Christ. The veil is lifted and I now do see Christ, in a mirror dimly. And I live waiting. Waiting to see him face to face - he who was crucified for me.