Ss. Basil and Gregory: "this is the promise that he made us"

... eternal life.
I write you these things about those who would deceive you.
As for you, the anointing that you received from him remains in you,
so that you do not need anyone to teach you.
But his anointing teaches you about everything and is true and not false; just as it taught you, remain in him.

-- 1 Jn 2:22-28

Jesus is Christ, "anointed," because the Spirit is his anointing, and everything that occurs from the Incarnation on derives from this fullness. When Christ is finally glorified, he can in turn send the Spirit from his place with the Father to those who believe in him: he communicates to them his glory, that is, the Holy Spirit who glorifies him. From that time on, this joint mission will be manifested in the children adopted by the Father in the Body of his Son: the mission of the Spirit of adoption is to unite them to Christ and make them live in him:

The notion of anointing suggests . . . that there is no distance between the Son and the Spirit. Indeed, just as between the surface of the body and the anointing with oil neither reason nor sensation recognizes any intermediary, so the contact of the Son with the Spirit is immediate, so that anyone who would make contact with the Son by faith must first encounter the oil by contact. In fact there is no part that is not covered by the Holy Spirit. That is why the confession of the Son's Lordship is made in the Holy Spirit by those who receive him, the Spirit coming from all sides to those who approach the Son in faith.

-- CCC 690

Art: Icon of Saint Basil. Source OrthodoxWiki.