How many persons are there in the Godhead?

There are three persons in the Godhead: the Father, the Son, and the Holy Spirit; and these three are one God, the same in substance, equal in power and glory.

Matthew 28:19 (NASB)

Go therefore and make disciples of all the nations, baptizing them in the name of the Father and the Son and the Holy Spirit.

Do you believe that God is one Divine being existing eternally in three persons: Father, Son, and Holy Spirit, all of whom are equally God in essence? 

Belief in the Trinity is an essential to the christian faith. All Christians from Acts to the present day have believed that God is Father, Son, and Spirit. Throughout christian history, the Godhead has been invoked during baptismal ceremonies. 

In believers baptism, Christians publicly identify themselves with the Triune Godhead.[1] During the baptismal ceremony, the baptizer invokes the Godhead saying, “I baptize you my brother, in the name of the Father, the Son, and the Holy Spirit.”

[1] Believer's Bible Commentary, Matthew 28:19, 20.