This is a symbol of baptism, which now saves you-- not the putting away of the filth of the flesh, but the answer of a good conscience toward God, through the resurrection of Jesus Christ,
But the interrogation of a good conscience toward God ...  The word of the Lord seems to have been designed in order to give men who will not believe it some kind of crutch upon which to rely in their unbelief.  Someone has said, "There is hardly a text in the Bible that does not have a nail in it where the devil can hang his hat."  The word here falsely rendered "interrogation" is exactly that.  In the Greek language, as in the English, there are many words that have multiple meanings, some of those meanings being actually contradictory, and this is such a word.  In English, for example, the word "fast" may be applied to a horse that wins the Derby, or to one that is tied fast to a post.  Take the English word "cut":  (1) It means a mountain pass; (2) a wound inflicted by a knife; (3) to skip, as when one cuts a class; (4) the cut-off in golf tournaments; (5) to adulterate, as when hard drugs are cut, etc., etc.