It's true because well, it is. I'm not sure why you ask. Everyone knows someone who's faithful only in action and not in heart.
Noah survived because he had a heart for God in a world that did not. Not necessarily strictly because of "obedience" in the proper sense, and CERTAINLY not because he read scripture and understood it. The primary mode of determining ones eternal life is relationship with God. Noah, Moses, etc prove that before the scriptures were set as such.
Well Noah
Genesis 6:8 But Noah found favor in the eyes of Jehovah.
9 This is the history of Noah.
Noah was a
righteous man. He
proved himself faultless among his contemporaries. Noah walked with the [true] God.
2 Peter 2: 5 and
he did not hold back from punishing an ancient world, but kept
Noah, a preacher of righteousness, safe with seven others when he brought a deluge upon a world of ungodly people;
God asked Noah to build the Ark, which took 40 years. Noah also did preaching, to the people around him. But no one listened to him.
This flood account pictures our day
36 Concerning that day and hour nobody knows,
neither the angels of the heavens nor the Son, but
only the Father. 37 For
just as the days of Noah were, so the presence of the Son of man will be. 38 For as they were in those days before the flood, eating and drinking, men marrying and women being given in marriage, until the day that Noah entered into the ark; 39 and they took no note until the flood came and swept them all away,
so the presence of the Son of man will be.
So this says that people will just be living their lives and they will take no note , until it is too late.
So just like Noah's day if you want to survive you have to be doing the things God wants. Not what we want. He acutally has work for us to do.
When Jesus comes ( notice the bible uses the word presence here.) If you are not doing the work required, then you would be the same as the people at Noah's time. They didn't take any note of the signs, and just kept living our life , without doing God will.
The flood actually showed that God would bring to destruction to the whole world of mankind, and it would be very few who make it.
So we have to study and know what these things are that God wants us to do, and how to live.
That is why in an earlier post I said it is scary, to you say , we don't need to get an understanding of God.
So why Noah, and why no some other . that were around at that time.