This can be stated in active form. Possible meanings are 1) "the love of God" refers to a person loving God, and "perfected" represents completely or fully. Alternate translation: "it is that person who loves God completely" or 2) "the love of God" refers to God loving people, and "perfected" represents completing its purpose. Alternate translation: "God's love has achieved its purpose in that person's life" (See: [[rc://en/ta/man/jit/figs-possession]] and [[rc://en/ta/man/jit/figs-activepassive]])
The phrase "we are in him" means that the believer has fellowship with God. Alternate translation: "When we obey what God says, we can be certain that we have fellowship with him" or "By this we know that are joined to God" (See: [[rc://en/ta/man/jit/figs-metaphor]])