The Holy Spirit is the agent who grants a believer communion with the Father, the Son, and the Holy Spirit. This is a communion for which we were originally created and for which the Father elected the Son to redeem us. Salvation is not merely from the horrors of a real place called hell nor even merely also to the joys of a place called Heaven. Salvation is gained supremely through acceptance of the invitation to enter into an eternal relation with the Triune God!
(H)uman participation in the Trinity is derivative – by grace, not by essence. And in the spite of our created status, we are nevertheless granted a place with God, in relationship with all three subjects of the Trinity. For love He created us – Father, Son, and Holy Spirit. By grace He redeems us – Son, Father, and Holy Spirit. For communion He communes with us – Holy Spirit, Son, and Father. We are intended for life “with” and “after” Him.
Yarnell, Malcolm B. (2016). God the Trinity. Nashville: B&H Academic.