Anyone calling the Revolution and Founders sinful is a dumbass. And besides, it would be a minor sin. One fully covered by being redeemed.
Not a biggie.
I basically agree with your defense of our founding, but your view of red letters vs. Paul misses that the risen Lord Jesus Christ specifically called him as “a chosen instrument of mine to carry my name before the Gentiles and kings and the children of Israel” (Acts 9:15).
Jesus called Paul and thus gave him authority to teach. That’s why you have 13 letters from him in your NT. Those are Jesus speaking to YOU. That’s how he speaks, through chosen instruments.
Most of the “red letters” are Him speaking to Israel during His earthly ministry where he said “I was sent only to the lost sheep of the house of Israel.” (Matthew 15:24)