This passage is structured around 3 statements that begin with “Whoever says..”

Verse 4: Whoever says I know Him

Verse 6: Whoever says I abide in Him

Verse 9: Whoever says I am in the light

These are all synonyms for what it means to be a Christian. A Christian knows Christ, abides in Christ and walks in the light of Christ.

If you claim these three descriptions as a believer in Jesus, then there must be some concrete evidence or fruit to support your claim.