What does 1 John 2:5 mean?

In contrast to the "liars" of verse 4 are those who obey God's commandments. "Keeping" God's Word is another reference to obedience. According to John, God's love is perfected in those who obey the Word of God. The term "perfected" does not refer to 100 percent flawless living, but rather to maturity. No one is perfect (Romans 3:10), but all believers are called to growth and maturity; this is a process of perfection. While this is expected, it is not guaranteed.

As with verse 4, there are alternate interpretations of what verse 5 implies. Those who truly know Christ grow to live like Christ. Their actions give evidence of their relationship. Those who do not progress in their Christian walk fail to give positive evidence that they are saved. This should not, however, be mistaken as salvation based on works or good deeds. Only God knows the heart (Acts 15:8), but our lives can reveal whether our hearts have been changed by Christ or not. Nor are verses 5 and 6 meant to be a test of a person's salvation.

In the immediate context, John is speaking of a person's relationship and fellowship with God. This parallels John 15:1–8, where those who do not "abide" in Christ lose all ability to produce good fruit. This is not a loss of salvation—which is secure once obtained—but it certainly applies to the consequences of choosing sin over righteousness.

Regardless of interpretation, this verse points to a clear statement in verse 6: that believers "ought to walk" as Christ did. Whether or not we do is up to us.