1 John 2:23-25

Whoever denies and repudiates the Son does not have the Father; the one who confesses and acknowledges the Son has the Father also. As for you, let that remain in you [keeping in your hearts that message of salvation] which you heard from the beginning. If what you heard from the beginning remains in you, you too will remain in the Son and in the Father [forever]. This is the promise which He Himself promised us—eternal life.