I do not understand the interpretation of I Peter 3:18-22. I read the web site but I still do not understand why this Scripture is so important. Please tell me.
Since I don't know what you don't understand, I don't know what more is need beyond the explanation given in the lesson "How Noah was Saved."
All Scripture is important, though different passages are important for different reasons. "All Scripture is given by inspiration of God, and is profitable for doctrine, for reproof, for correction, for instruction in righteousness, that the man of God may be complete, thoroughly equipped for every good work" (II Timothy 3:16-17). God put I Peter 3:18-22 in our Bibles for a reason and it is important that we understand what He wanted us to know. "Therefore do not be unwise, but understand what the will of the Lord is" (Ephesians 5:17).