'Union' in the Bible
But whoever continually keeps his commandments is the kind of person in whom God's love has truly been perfected. This is how we can be sure that we are in union with God:
As for you, let the teaching which you have received from the very beginning continue in your hearts. If that teaching does continue in your hearts, you also will continue to be in union with the Son and with the Father.
And as for you, the anointing which you received from Him remains within you, and there is no need for any one to teach you. But since His anointing gives you instruction in all things--and is true and is no falsehood--you are continuing in union with Him even as it has taught you to do.
And now, dear children, continue in union with Him; so that, if He re-appears, we may have perfect confidence, and may not shrink away in shame from His presence at His Coming.
No one who remains in union with him keeps on sinning. The one who keeps on sinning hasn't seen him or known him.
The man who obeys His commands continues in union with God, and God continues in union with him; and through His Spirit whom He has given us we can know that He continues in union with us.
No one has ever yet seen God. If we love one another, God continues in union with us, and His love in all its perfection is in our hearts.
We can know that we are continuing in union with Him and that He is continuing in union with us, by the fact that He has given us a portion of His Spirit.
Whoever acknowledges that Jesus is the Son of God--God continues in union with him, and he continues in union with God.
And, as for us, we know the love which God has for us, and we confide in it. God is love, and he who continues to love continues in union with God, and God continues in union with him.
In this [union and fellowship with Him], love is completed and perfected with us, so that we may have confidence in the day of judgment [with assurance and boldness to face Him]; because as He is, so are we in this world.
We also know that the Son of God has come and has given us understanding so that we may know the true God. We are in union with the one who is true, his Son Jesus the Messiah, who is the true God and eternal life.