Christ crucified is both a sign of the ultimate consequence of evil, and of the ultimate victory of Christ over evil through the power of suffering love.
What God has promised, God will make good on, no matter what the apparent obstacles, and our job is simply to set about cooperating with the promise-maker rather than with the obstacles.
The Transfiguration points us back to Jesus’ baptism and forward to his resurrection, and reiterates that the only way from one to the other is the way of the cross.