I John 4:6 “We are of God: he that knoweth God heareth us; he that is not of God heareth not us. Hereby know we the spirit of truth, and the spirit of error.”
To be “of God”, in this context, is to have been chosen and originated by “God”, is to be a direct spiritual descendant of “God”, is to be guided by “God”, is to be physically and mentally empowered by “God”, is to have been Eternally Saved by “God”, is to be Eternally Secure by “God”, is to be Eternally loved by “God”, and is to have “God”-given faith to live by in this present life. Those who “are of God” are those that “God” the Father “hath chosen … in him [Jesus Christ] before the foundation of the world, that” they “should be holy and without blame before him [God the Father] in love” (Ephesians 1:4). They were made to “be holy and without blame before him” when our Blessed Savior Sacrificed Himself to “save his people from their sins” (Matthew 1:21), not by any act of their own. These are the “Elect according to the foreknowledge of God the Father, through sanctification of the Spirit, unto obedience and sprinkling of the blood of Jesus Christ” (I Peter 1:2). That is, it was “God” Who Elected them to be His very own, it was “God” who Sanctified them, it was Christ’s “obedience” and the “sprinkling of” His “blood” that Justified them before God the Father and Saved them to Eternal Heaven. These are made to greatly rejoice because “God” is their Father, “God” is their Elder Brother (Savior), and “God” is their Comforter; and in this life, “God” is their “friend that sticketh closer than a brother” (Proverbs 18:24)! We have every reason to “Rejoice in the Lord alway: and again I say, Rejoice.” (Philippians 4:4)!