"Sin", "Justice" and the suffering of innocents?

It is common to regard the suffering (and death) of "innocents" such as young children, babies, unborn babies; as especially difficult for Christianity to explain or justify. This derives from the assumption that the suffering and death of the wicked is justified, in proportion to the degree of wickedness.

But, at least since Paul, much of official Christian doctrine emphasizes that there are no innocents, All Men are sinners - and this state is original and inescapable. 

Therefore, the argument goes; it is justifiable and expected that because all are guilty of sin, then everybody deserves to suffer and and die - and ought to expect this. 

This sees god the creator as essentially a judge - despite that this characterization removes a motive for creation in the first place! 

Justice works as a secondary means to some other end; but when accorded primacy, justice points towards annihilation as the only and final solution to a situation of endemic and intractable sin.

It seems to be natural and spontaneous to regard the demands of justice as the reason for inflicting suffering and death on transgressors; but commonsense falls to pieces when everybody dies, everybody suffers, and there is no strong or clear proportionality between degree of sin and of suffering. 

...For instance, when the chosen people or worshippers of the true-God are conquered or enslaved.

Also, when it is believed that everybody is a sinner and justifiably suffers and dies; and when this is combined with a dogma of god as omnipotent creator of everything from nothing... 

Then we get a god who created everything, and then found it Bad.