1. What is the mark of those who are born of God, according to verse 5?
  2. How do we demonstrate our love for the children of God, as mentioned in verse 2?
  3. What is the love of God, and how is it connected to keeping His commandments, as stated in verse 3?
  4. How does faith overcome the world, and what is the key to this victory, as mentioned in verse 4?
  5. Who is the one who overcomes the world, and why is it significant, as stated in verse 5?
  6. What is the significance of Jesus coming by water and blood, and how does the Spirit bear witness to this, as mentioned in verse 6?
  7. Who are the three that bear record in heaven, and how are they one, as described in verse 7?
  8. What are the three witnesses on earth that agree in one, as stated in verse 8?
  9. Why is the witness of God greater than the witness of men, as mentioned in verse 9?
  10. What is the record that God has given about His Son, and what does it mean for us, as stated in verse 11?
  11. What is the significance of having the Son and having life, as mentioned in verse 12?
  12. What assurance do we have as believers in the Son of God, according to verse 13?
  13. What is the confidence that we have in God, and how does it relate to our prayers, as mentioned in verse 14?
  14. What is the condition for our prayers to be heard and answered, as stated in verse 15?
  15. What is the distinction between a sin unto death and other sins, and how should we respond to each, as mentioned in verse 16?
  16. What is the nature of unrighteousness, and is there a difference between sins, as described in verse 17?
  17. What is the difference between being "born of God" and being "begotten of God," and how does it relate to sin and protection from the wicked one?
  18. How do we know that we are of God, and what is the contrast with the world, as stated in verse 19?
  19. What understanding has been given to us through the coming of the Son of God, and how does it relate to truth and eternal life, as mentioned in verse 20?
  20. What is the warning or instruction given in verse 21, and why is it important?

These questions can help explore the themes of being born of God, loving God and His children, the love of God and keeping commandments, the victory of faith, the significance of Jesus' incarnation and sacrifice, the witness of the Father, the Son, and the Holy Spirit, the witness of God and men, the record God has given, the significance of having the Son, the assurance of eternal life, the confidence in prayer, the distinction between sins, the nature of those born of God, the contrast between the true God and the world, and the warning against idols.