Final answer:
John taught in 1 John 1:7 and 9 that all Christians need to be purified.
Step-by-step explanation:
In 1 John 1:7 and 9, the apostle John teaches that all Christians need to be "purified" through the blood of Jesus Christ. The verses emphasize the transformative power of Christ's sacrifice for believers. In verse 7, John states, "But if we walk in the light, as he is in the light, we have fellowship with one another, and the blood of Jesus, his Son, purifies us from all sin."
This highlights the idea that living in accordance with God's truth and righteousness brings about purification through Christ's atonement. Verse 9 further reinforces this, declaring, "If we confess our sins, he is faithful and just and will forgive us our sins and purify us from all unrighteousness." The call to confession and acknowledgment of sin underscores the continual need for purification and the redemptive grace found in Christ for all Christians.