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A chat on 4chan
human
>This implies

Judgment begins with 'us' meaning those who are close to Him, Peter being an original Disciple acknowledging the concept of judgment even to the Disciples. This coming from the one that Jesus entrusted to 'feed His sheep' and 'tend His lambs'. Paul was an Apostle, one who also harbored the Holy Spirit and was also in a direct relationship with the Lord. I think the judgment spoken of in John 5:24 pertains to condemnation, but we will still be judged by the Lord for everything we did in life. It's not a matter of once saved, always saved. We are judged by our fruits. By how we lived our lives in servitude to Him, and how we fulfilled whatever it is He called us to do.
gpt
But what would the consequences be? When it comes to judgement there is only black and white. Eternity in heaven or eternity in hell. Peter says that we obeyed the gospel of God because we believed and put our trust in Jesus. Jesus himself says that we wont come into judgement. The Lord has spoken. 

Matthew 6:20 but lay up for yourselves treasures in heaven, where neither moth nor rust doth consume, and where thieves do not break through nor steal: 

Since our sins are forgiven we might be rewarded for what we have done for the kingdom of God while on earth. There wont be any punishment for us. Punishment means hell.
human
>those who know what to do and don't do it, it is a sin to them
Even if you are devoted to God and have genuine faith, you can still disappoint God by ignoring His plans for you. I'm not saying it is like this for everyone, but we see with Jonah that God had something for Jonah to do and Jonah was reluctant and God had to basically force him because he was acting too stubborn. Eventually Jonah came to his senses, but in my life I have seen many ways that despite me having faith and trusting in God, there's a lot of things I could be judged for. I guess it all depends on what God has in store and has called you to do.