During the third century, a heresy arose which is called “Modalism” or “Sabellianism” or “Monarchianism.” According to this heresy, the Father, the Son, and the Holy Spirit are all divine, but they are not distinct persons.
WILLIAM LANE CRAIG
Modalism is a heresy that denies the doctrine of the Trinity. Often surprising to some Christians, United Pentecostals ascribe to this ancient heresy. Modalism teaches that God is a single person who has eternally existed and yet He has revealed Himself in three modes, or forms.
Modalism rejects the Trinitarian belief that God exists at all times as three distinct Persons—Father, Son, and Holy Spirit. Rather, the modalist believes that God is one person made known in three modes. In the Old Testament, God manifested Himself in the mode of the Father. With the incarnation, God manifested Himself in the mode of the Son. Following Jesus’s ascension, God made Himself known through the mode of the Holy Spirit. Problematically, modalism rejects that the Father, Son, and Holy Spirit exist simultaneously, which means that modalists deny the distinctiveness of the three Persons in the Trinity.
This problem is compounded when you consider the baptism of Jesus. At His baptism, we see all three Persons of the Trinity present. The Father speaks from heaven, the Son is baptized, and the Spirit descends upon Jesus like a dove (see Matthew 3:16-17). Furthermore, after His resurrection Jesus told His disciples to baptize people in the Name of the Father, Son, and Holy Spirit (Matthew 28:19). New converts were to be baptized in the One Name (i.e. God) who exists in three Persons (namely the Father, Son, and Holy Spirit).
The problem is obvious—to embrace modalism is to reject the Trinity.
And to reject the Trinity is to reject orthodox Christianity.
Thought to Ponder
Modalism rejects Trinitarianism for a more nuanced form of Unitarianism.
Memory Verse
The grace of the Lord Jesus Christ and the love of God and the fellowship of the Holy Spirit be with you all (2 Corinthians 13:14).
One-Minute Apologist Video : Bobby Conway, “What Is Modalism?”
Life Less Ordinary 
Spot on.
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thanks
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Nice. Knowledge is necessary to help bring others to the truth.
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Hello. I’ve just left the “Oneness Pentecostal” movement after having been in deep for 15 years, even graduating from their 3-year bible college. That means I have A LOT to undo. So I would ask you to help me understand how these would be explainable as fitting the Trinitarian model.
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Under the orthodox Trinitarian model, Father/Son/Holy Ghost are three distinct, co-eternal, co-existant and co-powerful ‘persons’ that make up the Godhead. Yes, Jesus (Son) declared that he had no power, and that it was the Father doing the work.
Joh 14:10 Don’t you believe that I am in the Father, and the Father in me? The words that I tell you, I speak not from myself; but the Father who lives in me does his works.
This seems like a pretty circular loop, that the Father dwells in the Son and through the Son ‘doeth the works’.
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Likewise, when the Son (flesh) was conceived in Mary, it was not the Father who sired the child, rather it was the Holy Spirit.
Luk 1:35 The angel answered her, “The Holy Spirit will come on you, and the power of the Most High will overshadow you. Therefore also the holy one who is born from you will be called the Son of God.
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Lastly, the biggest mystery of the Godhead if trying to understand the Trinitarian model, is that Father, Son and Holy Ghost all dwelled in Jesus … so Three of the Godhead dwelt in One of the Godhead…
Col 2:9 For in him dwelleth all the fulness of the Godhead bodily.
I look forward to reading the understanding of this. This and many other examples makes the Modalistic argument ‘make sense’.
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The Bible is not an easy book to wrap your head upon. Consider the creation of the world. It’s a simple statement in the bible, but even the most renowned scientist have a tough time trying to explain it, far be it from the Bible. When you are a kid studying physics we take it for a fact when our teachers tell us force= mass x acceleration. I could go into details trying to explain, but I think Google would do a much better job than me. Cheers. I hope you find your answers
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This is the problem…When presented with Scriptural, the Trinity can only be a ‘unexplainable mystery’. I’ll keep digging.
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