Board Thread:Bible Games/@comment-31246436-20161025190507/@comment-1777104-20161202202642

The answer to that is found in Romans 1.  Not knowing Yahweh as God does not exempt one from the responsibility for sin.  Each of us have a conscience that knows instinctively what is right.  For our own reasons, we will go against that inner knowledge and incur guilt.
As for innocent infants, there are none.  The guilt of the elect infants (which may be all of them, but that is not easily defended from the Bible) is covered just like that of the elect adults -- by the death, resurrection and ascension of the Lord Jesus Christ.
The bottom line is that God will show mercy on some, and pour out his wrath upon the unrepentant. Mercy is not universal, or it would not be mercy. God is the one who judges sin, and only those who believe have had that judgment covered by Jesus. There will be a judgment day, and God is the Judge. Before that, judgment comes along the way as typological of the Final Judgment. 
The atheist's rejection of the reality of judgment is a primary reason for much of their unbelief. They read the Bible selectively and condemn God for doing what He said He would do. The teaching of the love and mercy of God is never meant to be universally applied. There are two humanities (Psalm 1) -- the Righteous and the Sinners. The two paths lead in opposite directions.