It doesn't matter who I speak for. I've known some very Holy people. But no perfect ones. If you say you don't sin, the truth isn't in you. And being a faker is being a Pharisee. You don't want to be that.
We walk by faith and not by sight. Noah was called a preacher of righteousness (2 Peter 2:5). So he preached righteous living.
"And spared not the old world, but saved Noah the eighth
person, a preacher of righteousness, bringing in the flood upon the world of the ungodly; And turning the cities of Sodom and Gomorrha into ashes condemned
them with an overthrow, making
them an ensample unto those that after should live ungodly;" (2 Peter 2:5-6).
Only eight people survived the global flood. Eight. So if you lived during the time of Noah and you heard him preach righteousness, you could say to him that he is lying because you have not seen anyone who lived righteously on the Earth. Problem. Everyone during that time besides Noah and his family were living in wickedness and or ungodliness. So you could not judge Noah based on your experience.
Imagine if you held to "Believe Alone-ism" back then.
"Hey Noah, I believe you." "I think the Ark can save me!"
But if you believed this but you did not do the good work of going into the Ark, then you would perish along with everyone else. Some form of action or work needed to take place as part of faith or a belief.
What you fail to realize is that verse 6 in 2 Peter 2 says that the global flood and Sodom were all examples to those who live ungodly thereafter. So yeah. Sin destroys. It destroyed whole cities and an entire world.