In honor of Basil the Great, the defender of the deity of the Holy Spirit, let us consider his argument from Matthew 28:19 regarding the equality of the Holy Spirit with the Father and Son:

For if our Lord, when enjoining the baptism of salvation, charged His disciples to baptize all nations in the name “of the Father and of the Son and of the Holy Ghost,” not disdaining fellowship with Him, and these men allege that we must not rank Him with the Father and the Son, is it not clear that they openly withstand the commandment of God? If they deny that coordination of this kind is declaratory of any fellowship and conjunction, let them tell us why it behoves us to hold this opinion, and what more intimate mode of conjunction they have.

If the Lord did not indeed conjoin the Spirit with the Father anti Himself in baptism, do not let them lay the blame of conjunction upon us, for we neither hold nor say anything different. If on the contrary the Spirit is there conjoined with the Father and the Son, and no one is so shameless as to say anything else, then let them not lay blame on us for following the words of Scripture. (On the Holy Spirit, X.24)

Basil argued that the command of our Lord to baptize “in the name of the Father, the Son, and the Holy Spirit” is evidence that we should understand the Holy Spirit to be equal with the Father and Son. He fought against those who wanted to see the Holy Spirit as something less than God or as something created and inferior to God.