If there ever was a "spark of goodness" lurking inside a now fatally abscessed and fallen nature of man, it really should have kindled up and come to the fore during the Garden crisis, in an hour of extreme need. But the Scriptural narrative is crystal clear about it. There was no spark, beyond that of the crackling motor neurons which triggered a panicked leap into the bushes.
Too bad for man. Our gracious Lord God, after all, extended an unmerited mercy to the arrogant murderer Cain, when the rascal pathetically whined about his suddenly becoming stalker's meat (Gen 4:13,15). So who's to say what would have happened, had Adam and Eve simply bent the knee and whispered: "Against You, You only have I sinned and done evil in Your sight ... Create in me a clean heart, O God, and renew a right spirit within me (Nota bene: I deduce here from the tip of St. David's own pen, that he diagnosed that "spark" thing as having gone kaput, with a single bite). Cast me not away from Your Presence, and take not Your Holy Spirit from me. Restore to me the Joy of Your Salvation, and uphold me with a willing Spirit."
Curiously, in sharp contrast to brat Cain, our first parents made no tantrum about their own punishments being altogether tougher than they could possibly bear. And we're talking a strong dose of reality here: birthing with pain, pestiferous weeds, sweating sorrows, and an ignominious return to dust ... not some hallucinated victimhood, at the hands of bounty hunters. Instead, the first couple's psychological and behavioral instincts were to flee and hide from the Spark (of better, the Light) of Holiness; and in the special case of the Old Man, the floundering leader of the one-flesh unit, to slime God for creating something (i.e., Adam's wife, and a relationship), which had been earlier described as "good" (Gen 1:31; cf. Gen 2:18) .
So what stopped any self-serving, impulsively kicking ruckus by the 'One-Flesh?' Ah, well, not the lack of ability, certainly; for Cain's sparkless antics duly establish the heritability of stinking, deeply ingrained and horribly metastasized sin ... embedded in a nature which our Brother, our Lord Jesus Christ, carried absolutely flawlessly for us (see the Book of Concord's just whipping of the Flacian baloney, for details). Adam murdered his wife, with his cutting remarks; and Cain murdered his brother, maybe with a cutting hoe for all I know. Like son, like father. And the latter could whine; this we know, along the paraphrased lines of "God, it's Your fault. What'd I ever do, besides maybe take an innocent snooze and then eat some, to deserve this mortifying development?" The difference from junior's attitude, of course, is that the Old Man is never portrayed by Moses as summing things up as "AND I JUST CAN'T TAKE IT ANYMORE!"
No. I think Adam and Eve were spirit-calmed ... their pitiless demons cast out, like those of an agitated Gadarene... by the healing Promise of an Incarnate Rescuer-God (Gen 3:15), and the forgiving Divine gift of bloodied skins to cover their pock-marked nakedness (Gen 3:21). For as Lutherans insist (or should), there's nothing like Word and Sacramental Mystery to sooth the savage soul.