A.T. Robertson Commentary 1 John 4:17

"Herein is love made perfect with us, that we may have boldness in the day of judgment; because as he is, even so are we in this world." — 1 John 4:17 (ASV)

Herein (εν τουτω). It is not clear whether the ινα clause (sub-final use) is in apposition with εν τουτω as in Joh 15:8 or the οτ clause (because) with the ινα clause as parenthesis. Either makes sense. Westcott argues for the latter idea, which is reinforced by the preceding sentence.

With us (μεθ' ημων). Construed with the verb τετελειωτα (is perfected). In contrast to εν ημιν (verses 12,16), emphasising cooperation. "God works with man" (Westcott). For boldness (παρρησιαν) in the day of judgment (only here with both articles, but often with no articles as in 2 Peter 2:9) see 2:28.

As he is (καθως εκεινος εστιν). That is Christ as in 2:6; 3:3,5,7,16. Same tense (present) as in 3:7. "Love is a heavenly visitant" (David Smith). We are in this world to manifest Christ.