1 John 3:24 And he that keepeth his commandments dwelleth in him, and he in him. And hereby we know that he abideth in us, by the Spirit which he hath given us.
This is the promise: we will live in God and God will live in us. This mutual indwelling is a kind of mysterious unity as both God and I are in each other. It is not easy for us to imagine exactly how this works out in real life. Who is doing what? A simple answer is: if it’s a sin, I am doing it; if it’s a good work, the Spirit is doing it through us.
The Holy Spirit is working in us so ”under the radar” that we don’t don’t easily see what He has done; this invisibility is so blurred that we take credit for the good works we do. A good work is God’s work. For this reason it is called the fruit of the Spirit. Our proper response is to praise and thank Him always; this response helps us believe the indwelling promise.
How do we dwell in Him, and how do we know we are? We dwell, and we know we dwell by ”keeping his commandments.” The previous verse (v. 23) defines ”his commandment” as this: believe on the name of Jesus, and as a result you will love one another as the fruit of faith. Fruit is the outward evidence of inward faith. ”By their fruits you shall know them.” Jesus says, ”Abide in me and you will bear much fruit.”
This wonderful promise is based on “the Spirit which he has given us.” The Holy Spirit seldom gets the credit He deserves, but that is because He glorifies Jesus always.