Summary: The second purpose of spiritual growth is that we become focused and not forgetful.
I remember the first time I had to wear corrective lenses when I was in college. Before that, I have always assumed that my eyesight is normal. I noticed that I have trouble seeing things from afar. But I just thought that the reason why I could not clearly see things from a distance was because they were far from me. So, I went to an optometrist and to my surprise learned that I got myopia or shortsightedness. I could clearly see things that are near but not those that are far. I remember I was on my way home from the optometrist and I clearly saw that I could not see things clearly. Everything suddenly appeared so fuzzy.
I think that’s the way it is in life. All along we thought that we see things clearly in life. We assumed we are living the normal life. But when we finally saw how God sees us through His Word, we realize that we are really out of focus. Let us read 2 Peter 1:9 (quickview) . “For whoever lacks these qualities is so nearsighted that he is blind, having forgotten that he was cleansed from his former sins.” Let us pray…
We already saw that we have to grow spiritually. According to verses 5 to 7 we have to “make every effort to supplement your faith with virtue… knowledge… self-control… godliness… brotherly affection… [and] love.” Verse 8 tells us: “For if these qualities are yours and are increasing, they keep you from being ineffective or unfruitful in the knowledge of our Lord Jesus Christ.” I already pointed out that the conjunction “for” in Greek means “reason” here in 2 Peter. Here in verse 8, the first reason why we must grow spiritually is that it makes us fruitful and effective.
Then verse 9 tells us what will happen when we don’t develop those qualities: “For whoever lacks these qualities is so nearsighted that he is blind, having forgotten that he was cleansed from his former sins.” Again, the conjunction “for” here means reason. The second reason why we must grow spiritually is that we become FOCUSED and not forgetful.
Was Peter talking here of believers or unbelievers? 2 Corinthians 4:4 (quickview)  regards unbelievers as blind people: “In their case the god of this world has blinded the minds of the unbelievers, to keep them from seeing the light of the gospel of the glory of Christ, who is the image of God.” But Peter was talking about a person who “is so nearsighted that he is blind”. The Good News Version goes like this: “you are so shortsighted that you cannot see”. He is not really blind. He is just nearsighted. He could actually see. But he is so out of focus that it is as if he could not see. He is as good as a blind person. Therefore, he was talking about a believer who became spiritually out of focus.
This nearsightedness is not something involuntary. According to the Bible Exposition Commentary, “A person has to be born again before his eyes are opened and he can see the kingdom of God. But after our eyes are opened, it is important that we increase our vision and see all that God wants us to see.” But instead of increasing his vision, this person closed the very eyes that God has opened. The word “nearsighted” is active in Greek. So, “the meaning may be ‘shutting the eyes to the truth,’ the intention being to emphasize the responsibility of the believer”. He chose not to see. He is blind by choice. He defocused himself. He did it voluntarily.