Q. 6. How many persons are there in the Godhead? A. There are three persons in the one God: the Father, the Son, and the Holy Spirit. These three are one God, the same in substance, equal in power and glory. (Westminster Shorter Catechism in Modern English)
In Eph. 1:3-4 and 1:13, the full Trinity participates in the work of salvation, choosing the redeemed for salvation in eternity past, redeeming us effectively through the death of Christ, and sealing us until final redemption appears. All three Members give divine wisdom for believer to live out the practical aspects of being assured, wealthy, and empowered in Christ—to do works that only can be done in the power of the Spirit (1:17; 5:18-20).
The Three appear when speaking of our access to God and the Temple to come (2:18,20); they work to reveal the love of God in Christ, deeply, to the believers (3:14-17); the Three are the basis of the unity in the local body of Christ (4:4-5).