What does 1 John 4:19 mean?

This short verse offers profound words. People do not wake up one day and decide to love (Romans 3:10). God is love, created love, and loved us first. John's summary of verses 17 and 18 also serves as a reminder. We are not to take credit for the love we have and show to others. God loved us, before we were capable of loving Him, and we can only love others because of what He has done in our lives.

As verses 20 and 21 will add, this love is not merely a mutual affection between us and God. It must also include love for others. Acting out of love is not exclusive to God in this context, but consists of loving both God and other people. This is the Great Commandment which involves loving God fully and loving neighbor as yourself. This teaching is also based upon the ancient Shema, or the Saying, from Deuteronomy 6:4–5: "Hear, O Israel: The LORD our God, the LORD is one. You shall love the LORD your God with all your heart and with all your soul and with all your might." The same is seen in Leviticus 19:18: "you shall love your neighbor as yourself: I am the Lord."