"All flesh had corrupted their way on earth"-Genesis 6:12. Why? Because of the Nephilim that populated almost the entire world/land depending on your views on whether the floodvwas local or global. Whilst many human children (as you may protest) were born during Noah's day, isn't it possible that most if not all of them were killed before the Flood? After all, the world at the time was described to be full of violence. Also, to assume that all children are inherently innocent when an act of divine judgement occurs appears to be a pathetically modern humanist interpretation. Sorry but unless the Bible elaborates on why the children have to die in an act of divine judgement (eg the plague on the firstborn, the death of David's newborn son with Bathsheba, the divinely ordained Assyrian and Babylonian invasions against Israel and surrounding nations in the Middle East etc), then we have to presume the blunt truth that the children were as wicked as men. To assume otherwise is collective punishment/euthanasia. Remember that there were young people at Sodom who wanted to rape the angels Lot protected (Genesis 19:4). Remember that demons wanted to possess children especially in the NT times.

I don't know if it really qualifies as a justification, but what if those children died so they could go to Heaven immediately upon their death? Was that cruelty or blessing? As a Reformed Baptist I believe in the view that those who die before reaching an age of discretion thus die without deliberately sinning. Such souls go to Heaven. They go to Heaven not because they are sinless... they still have a fallen sinful nature, but they are regenerate through the redeeming work of Christ. They are regenerate, so if they could have they would have shown their faith that Christ died for them.

This view can be seen in the sermon by the (19th century) Reformed Baptist minister Charles Haddon Spurgeon here:

https://www.metropolitantabernacle.org/Christian-Article/Infant-Salvation-Charles-Spurgeon/Sword-and-Trowel-Magazine

Not all Reformed Baptists believe the same as this. For me, I think any alternative to this, such as God sends some of these children to everlasting hell because of their sinful nature, it is quite abhorent to me, and seems extremely remote from the loveliness of our Saviour's character.

This question asks for "all denominations", which isn't generally allowed. The resulting "correct answer" would either be a large collection of individual answers, one for each denomination, or a single answer that covers them all and is incredibly wrong.

In case this question doesn't get closed for that reason, I will however offer one additional justification (a very specific variation of #1).

Most mainstream Christian denominations believe that we have immortal souls that survive our deaths. Those that are saved go to live in Heaven; those that are condemned go to live in Hell; and some (e.g. Catholics) will go to Heaven after being sufficiently tortured/punished/cleansed in Purgatory.

This answer doesn't represent those denominations.

There are other denominations that believe that:

• We are mortal souls ("The soul that sinneth, it shall die." — (Ezekiel 18:4) and (18:20)).
• Throughout history, before Christ's return, most people will be deceived by Satan, the god of this age (2 Corinthians 4:4), and follow false religions, including false forms of Christianity (2 Corinthians 11:4). Only a very small number of true Christians will be saved.
• Those saved people will be resurrected as immortal spiritual beings and rule with Christ in the Kingdom of God during the Millennium (first resurrection (Revelation 20:6 )).
• Following the Millennium, all the people that have ever lived and died, without ever being called and accepting Jesus as their saviour, will be resurrected as physical humans (second resurrection (Revelation 20:5)).
• They will then live out their lives on Earth, learning about God's truth and way of life, and the vast majority of them will be converted and saved (2 Peter 3:9).
• This is not a "second chance" at salvation, it is their first and only chance.
• At the end of the age, everyone not previously resurrected (because they were called by God and rejected salvation) will be resurrected (third resurrection) and will join those remaining people that still haven't accepted salvation.
• This relatively small group of unrepentant people will be totally destroyed and burned to ashes (Revelation 20:15). They will no longer exist.

The "innocent children" asked about in the original question will obviously be in the second resurrection, as will millions of other people that were killed as a result of God's seemingly callous decisions and not because of their own fault.

For them, that second life will appear to continue immediately after their deaths. Their first death was but an inconvenient blink of an eye.

God knows that these innocents will have their chance to live and have salvation during their second life on Earth. That they had their first lives interrupted isn't nearly so bad as it seems.

Their first deaths are neither immoral, cruel, nor unjust.

Headship: the choices of leaders affect those under them

The concept of Headship is very important for understanding how judgement and justice play out in the Old Testament, and even in the New Testament. Peoples and nations are judged because of the actions of their leaders:

• In Genesis 12 Pharaoh's household is afflicted by plagues because Sarai was taken into his house when he didn't know she was Abram's wife
• Egypt is judged when the Pharaoh would not let Israel leave
• Israel is judged when David took a census (2 Samuel 24, 1 Chronicles 21)

This concept is taken up in the New Testament to explain how sin has taken over all of humanity because of Adam our father's sin, and how the obedience of one man Jesus can save us (Romans 5, 1 Corinthians 15). Original sin means that we are all tainted by sin, in need of redemption, even though a infant may not yet be capable of consciously rebelling against God. In the same way, while some Egyptians may have hated the Israelites, others would not have, and yet were afflicted by the plagues all the same. When David ordered a census there is no suggestion that the whole of Israel shared in his guilt, and yet they shared in his judgement.

So in the time of Noah, we can understand that yes, every human was a sinner, but the judgement of the flood was not a sign that every human was consciously rebelling against God. As the head of households made decisions for their families, the results affected everyone. We see this not just in those who die, but even those who are saved: it is Noah alone who is righteous (the pronoun you is singular), and so his family is saved because of him, not because they merit it themselves.

Then the LORD said to Noah, "Enter the ark, you and all your household, for I have seen that you (singular) alone are righteous before me in this generation. (Genesis 7:1, CSB)

But God judges us for our own personal sins

Ezekiel 18 is a long and detailed discussion of how God judges us as individuals. The principle is clear: God is just and judges us so that we die for our own sins, not the sins of our fathers or our children.

But we know from innumerable examples in the Bible that people do die for the sins of others. We've just seen the examples of judgement of nations for the sins of their heads. Numbers 14:18 says that God "punishes the children for the sin of the parents to the third and fourth generation".

The best way I can see to reconcile these ideas is that Ezekiel 18 is talking about our eternal judgement, not the temporal judgements and punishments God deals out. When we stand before the judgement throne of God, we will answer for our sins alone. No one will receive the eternal death of hell for the sins of another. But we can die in this life for many reasons, not just our own sins.

This suggests that even the direct judgements of God in scripture do not always imply that the judged will be eternal condemned. 1 Corinthians 11:30 says that participating in communion in an unworthy manner is the cause of many of the church being sick or even asleep, meaning dead. But this is called in verse 32 discipline, not condemnation. In Acts 5 Ananias and Sapphira die when they lie to the Holy Spirit. Does this mean they were never truly saved, or that they lost their salvation? The text doesn't directly imply that. In Joshua 7 Achan and his family is executed for disobeying the instructions of God, after first confessing his sins before Joshua and the community. We can't know his heart, but the text is not incompatible with Achan genuinely repenting, even though that does not stop the temporal punishment. God never promises to rescue the repentant from all temporal consequences for sin, and indeed even temporal punishments from God.

If you're still following me, then the answer to this question about the killing of children during Noah's flood is that they were killed because of their parents' unwillingness to repent and turn back to God, and yet this temporal judgement is not the end of the matter. They, like everyone else, will be judged on judgement day for their own sins and no one else's.

There is another way to look at this question: There is nothing different about the death of people who died in the flood and people who have died throughout history in the millenia since.

The maximum age at death recorded in the Bible is 969 years, for Methuselah. To Noah, God revealed that he would henceforth limit the maximum lifespan for humans to 120 years. This is an eightfold reduction in the maximum lifespan. Since we do not see a terribly abrupt cutoff in the distribution of people's longevity today, we can assume that God did not just add a cutoff, he shifted the whole curve.

Today, 25% of people in the world are 14 years old or less. This was higher in the past, but childhood mortality has been declining due to better nutrition and medicine. However, in Noah's day, it is likely that childhood mortality was similarly low, compared to conditions after the flood.

If we apply an eighfold shift to the curve, then that means that in Noah's day, only 3% of people were aged 14 or less. That means that the flood of Noah killed fewer infants and young children than is the common situation throughout of most history since then. Stillbirth, infant diseases and starvation, child sacrifice, child abuse, war, weather, and all the other causes of death to children in the centuries since Noah probably have killed a higher percent of children than the proportion killed during the flood.

This reduces the question: "How can you justify causing the death of children in the flood of Noah?" to another question: "How can you justify God's taking of the life of any child at any time throughout history?"

In Luke 13, Jesus said this:

13 Now there were some present at that time who told Jesus about the Galileans whose blood Pilate had mixed with their sacrifices. 2 Jesus answered, “Do you think that these Galileans were worse sinners than all the other Galileans because they suffered this way? 3 I tell you, no! But unless you repent, you too will all perish. 4 Or those eighteen who died when the tower in Siloam fell on them—do you think they were more guilty than all the others living in Jerusalem? 5 I tell you, no! But unless you repent, you too will all perish.”

Jesus did not teach that the circumstances of a person's death correlate simply to how good or wicked that person's life was. The book of Job teaches the same thing. Job's friends confidently asserted that Job's children were exceptionally wicked because of the storm that killed them. They said the same thing about Job, by comparing his financial and physical condition to what they expected should happen to wicked people under God's judgment. God rebuked them strongly.

I know - I haven't answered the question. But the question as stated assumes a category of children that we do not need to deal with any differently than the children alive today. For that, Elihu's answer to Job in Job 37 is appropriate:

11 He loads the clouds with moisture; he scatters his lightning through them. 12 At his direction they swirl around over the face of the whole earth to do whatever he commands them. 13 He brings the clouds to punish people, or to water his earth and show his love. 14 “Listen to this, Job; stop and consider God’s wonders."

Sometimes suffering is punishment, and sometimes it is training that produces growth and is evidence of God's love.

As for what happens to those children, as a Reformed / Baptist believer, I believe that God welcomes such children into heaven.