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.
But we have not received the spirit of the world, but the Spirit which comes forth from God, that we may know the blessings that have been so freely given to us by God.
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.