Most Holy Trinity

St. Matthew 28.16-20: "Go therefore and make disciples of all nations, baptizing them in the name of the Father and of the Son and of the Holy Spirit, and teaching them to obey everything that I have commanded you. And remember, I am with you always, to the end of the age."

"We define that there are two, the Father and the Son, and three with the Holy Spirit, and this number is made by the pattern of salvation... [which] brings about unity in trinity, interrelating the three, the Father, the Son, and the Holy Spirit.  They are three, not in dignity, but in degree, not in substance but in form, not in power but in kind.  They are of one substance and power, because there is one God from whom these degrees, forms and kinds devolve in the name of Father, Son and Holy Spirit" (Tertullian).