In the Old Testament there are two types of angels: "the angel of God" and "the angel of the Lord". The "angel of God" is His Son, who is the image of the Father because the Son is filled with the Spirit (presence) of the Father and the Son obeys the Father. The Son becomes the physical image on the earth of the invisible God the Father. In the ancient Jewish custom of "agency", when someone is sent in the name of a ruler, he, as the agent of the ruler, represents the ruler in words and in power. The "angels of the Lord" represent the many inferior angels that are sent by the Lord, who is the Son of God. That is why the God of the Old Testament exhibited all those negative traits such as anger, grief, jealousy, and change of mind. God's Glory is the Father's Holy Spirit which allows the Father to enter the being of the Son. There is only one "angel of God", the Son. There are many angels of the Lord, and they are all filled with the Spirit of the Son whom they represent. The Son had this Glory (portal through which he was able to enter the beings indwelled) before the world was. He lost this glory when he became human, but regained it when he ascended back to the Father after his death and resurrection from the dead. He went back to the Father to get glorified so that he would be able to enter humans that he baptized with the Holy Spirit. These humans, chosen by the Father when He grants repentance for sins committed, are changed (born again) when they receive the "Promise of the Father" (the Son's Holy Spirit) through which the Son (and the Father through the Son) can enter the being indwelled and become part of the Spiritual Body of the Son (the real Church). It is the indwelling of the Father and the Son through the portal of the Holy Spirit that changes our motivation for living from love of self first to love of God first and all others as we love ourselves. That is how Jesus is one with the Father, and we become one with both the Father and the Son.You certainly cannot be a Christian without the Holy Spirit:
(Rom 8:9) But you are not in the flesh but in the Spirit, if indeed the Spirit of God dwells in you. Now if anyone does not have the Spirit of Christ, he is not His.