How does Celan use irony in the poem, Late and Deep?

Celan uses a special kind of irony in this poem. He sets his reader up to expect that the speakers of the poem are taking some sort of conversion oath, or are in some way praying to Christ and violating their Jewish faith. He moves from simple promises to grander and more portentous speech, invoking awesome miracles until he gets to the miracle that undercuts all previous speech. His assertion that no man has "come forth from the grave" lets careful readers know that all the previous language was not meant in the way it has seemed. If he swears on behalf of what he knows has never come, he cannot have meant his oath in the way it first seemed.