Did Noah of the bible warn his people?

The biblical account of the destruction of Noah’s people is vague and shows no detail on why Yahweh destroyed that nation. The question arises for what reason were those people punished?  The accounts of Noah’s story is found in the book of Genesis, starting from chapter 6 and ending at chapter 9. Those 3 crucial chapters fail to give a valid reason why that nation was punished. Christians normally point to Genesis 6:5 where Yahweh saw “wickedness in man on earth”. The text continues to describe how Yahweh grieved in his heart why he made man, and orders that the people of that land should be destroyed utterly.

⁵ And God saw that the wickedness of man was great in the earth, and that every imagination of the thoughts of his heart was only evil continually.

⁶ And it repented the Lord that he had made man on the earth, and it grieved him at his heart.

⁷ And the Lord said, I will destroy man whom I have created from the face of the earth; both man, and beast, and the creeping thing, and the fowls of the air; for it repenteth me that I have made them.

As you can read, Yahweh gave no valid reason why that nation should be destroyed. Now to answer Genesis 6:5 that the lord saw wickedness of man on earth, that is not a valid reason why they should be all destroyed. The reality is wickedness of man still remains on earth, in fact the people during the time of Jesus were also wicked, why were they not destroyed?

A wicked and adulterous generation seeketh after a sign; and there shall no sign be given unto it, but the sign of the prophet Jonas. And he left them, and departed. (Matthew 16:4)

Here Jesus is not only calling them “wicked” he is referring them as a “generation of wicked people” if being wicked is such an extravagant crime, why than did Yahweh keep them alive and not destroy them? After all they went against his “so called son” was that not enough to destroy them. There seesmt o be injustice going on toward a nation who had no warning from God. And this brings us to our second point. Were the people of Noah warned? And the honestly answer is no.

If we continue reading Genesis it reads in verse 8, “But Noah found grace in the eyes of the Lord.”  Noah found grace in the eye of God, yet this “so called loving God of the Bible” showed no mercy by sending Noah to his people as a warning so he could tell them to stop doing “wicked” and turn to God.

The ironic thing is, from chapter 6 all the way to chapter 9, not a single instance is it mentioned where Noah spoke to his people to turn to God or admonished them for the evil doing.  There’s also a change of theme in verse 12 Yahweh now blames the nation because they turned corrupt

^12 “And God looked upon the earth, and, behold, it was corrupt; for all flesh had corrupted his way upon the earth.”

Once again this is not a valid reason since Moses himself testified the Jews would turn to “corruption”

“For I know that after my death [i.e., after the death of Joshua, whom Moses considered like himself] you will corrupt yourselves and you will turn from the way that I commanded unto you, and the……” (Deuteronomy 31:29)

Just for the record the problem is not that evil people were destroyed, the problem that we have is why were they not warned by a Prophet who was among them, why did Noah being a Prophet not speak to them about there wrong doings. Why was Noah silent towards there wickedness? Why didn’t Yahweh tell Noah to go speak to his people and bring them back to God.

It is not possible for a Prophet of God to be among his people and keep silent. Every Prophet sent on earth came as a Warner for there people. They brought the message of God to save their nation from perishing, how comes nothing is mentioned about Noah preaching to his people? If those people were not preached and taught about God whilst a messenger was among them, then this is unjust towards them. They had no on to warn them. Why would God destroy a nation without warning them? Without giving them a chance.

Genesis says nothing at all about Noah preaching or warning anyone to repent. This idea is based on late Jewish and Christian traditions that date from around the turn of the eras and presumably arose to answer the question of why Noah didn't warn his contemporaries about the coming destruction.

Apart from the passage in 2 Peter 2:5 that describes Noah as a "preacher" or "herald" of righteousness (note that this text does not specify who Noah preached to or whether it was before or after the flood), the idea that Noah warned his contemporaries is found in Josephus, I Clement, the Sibylline Oracles and some Rabbinic writings. On the other hand, I Enoch attributes this preaching activity to Enoch (who reproves the Watchers) while Philo says that the antediluvians were given 120 years to repent but doesn't mention Noah preaching at all.

This late tradition of Noah the preacher is actually contradicted in the gospel of Matthew: As it was in the days of Noah, so it will be at the coming of the Son of Man. For in the days before the flood, people were eating and drinking, marrying and giving in marriage, up to the day Noah entered the ark; and they knew nothing about what would happen until the flood came and took them all away. (Matt 24: 37-39)

Here we are told that the pre-flood generation know nothing about the coming flood until it arrived.

With regard to the second part of your question, Genesis says nothing about the construction time for the ark

For this reason the story of Noah found in the Bible cannot be accepted a genuine by Muslims.