That (οπως). Rather than the more common final particle ινα. Connected with μνειαν ποιουμενος.

The fellowship of thy faith (η κοινωνια της πιστεως σου). Partnership like Philippians 1:5 in (objective genitive, πιστεως).

Effectual (ενεργης). Common adjective, like ενεργος (at work), in N.T. only here, 1. Corinthians 16:9; Hebrews 4:12. Papyri use ενεργος of a mill in working order, of ploughed land, etc.

In you (εν υμιν). Some MSS. have εν ημιν (in us), itacism and common.