The doctrine of the Trinity has been tried, tested, attacked, and redefined throughout the centuries. The Christian, in the face of these challenges, must stand up and give a reasoned defense of what the doctrine is. Moreover, the Christian must in this defense be thoroughly biblical, taking great care to enunciate what the Scripture says regarding the doctrine.
The following explanation of the doctrine of the Trinity is given (1) to encourage and edify the reader, and (2) to furnish the reader with an apologetic-type explanation of the doctrine in the hope that it would be used to communicate the doctrine to those who either struggle with it or deny it outright.
A presupposition is something assumed or taken for granted. For our purpose we shall assume three things: (1) the Bible is the word of God; (2) we are finite in knowledge and understanding; (3) God is infinite in nature. Therefore, although we cannot fully comprehend how the one God is three persons (because of presuppositions 2 and 3), we can nonetheless fully apprehend that the one God is three persons (because of presupposition 1). It now remains to explain the doctrine.
There are three sentences furnishing the explanation of the doctrine, each with Scripture to support them. I shall first state the doctrine, and then I shall elaborate upon the statement.
There is one God (Isa. 43:10). God is the Father (2 Pet. 1:17), and the Son (John 20:28), and the Holy Spirit (Acts 5:3-4). The three distinct persons are the one God (Matt. 28:19).
There is one God. Christianity is monotheistic–it believes in the existence of only one God: “Before Me there was no God formed, and there will be none after me” (Isa. 43:10). Other “so-called” gods (cf. 1 Cor. 8:5) do not in reality exist (cf. Gal. 4:8).
God is the Father. In 2 Peter 1:17 we have a person called the Father, and He is called God: “For when He received honor and glory from God the Father, such an utterance as this was made to Him by the Majestic Glory, ‘This is My beloved Son with whom I am well-pleased.'”
And the Son. In John 20:28 Thomas confesses Jesus as both Lord and God. We therefore have a person called the Son, and He is called God: “Thomas answered and said to Him, ‘My Lord and my God!'”
And the Holy Spirit. Peter in Acts 5:3 exclaims, “Ananias, why has Satan filled your heart to lie to the Holy Spirit?” He then states that Ananias has “not lied to men, but to God” (v. 4). Here we have a person called the Holy Spirit, and He is called God.
If there is only one God, and we have three persons in the New Testament that are called God, we must conclude that somehow the three persons are the one God (remember our presuppositions).
The three distinct persons are the one God. Matthew 28:19 states, “baptizing them in the name of the Father and the Son and the Holy Spirit.” The “name”–the authority–into which believers are baptized and are identified with is “of the Father and the Son and the Holy Spirit.” “Name” is singular, and consists of the three distinct persons. Why distinct? A Greek grammatical rule states that when two or more nouns (must be personal, singular, and non-proper names) are connected by “and” (kai) and are each preceded by the definite article “the,” they must be understood as separate and distinct. Here we have three nouns (Father, Son, Holy Spirit) that are each preceded by the definite article “the” (tou) and are separated by “and” (kai):
eis to onoma tou patros kai tou
in the name of the Father and of the
huiou kai tou hagiou pneumatos
Son and of the Holy Spirit
In part, it is for this reason the Church believes that the one God (the one name, the one authority) with whom believers are identified, and by whom believers are owned, is the Father and the Son and the Holy Spirit, and that the three distinct persons exist simultaneously as the one God.