From all that i can find, a single quote of Pastor @stevenfurtick 's (saying that Christ was 'changing form' when departing from the disciples) is the basis of the accusation of his heterodoxy and dismissal of Trinitarian G-dhead.

This is despite his own claim of embracing a Trinitarian view of G-d the Father, Son, and Holy Spirit, so there is subtlety beyond the face of it that invites further investigation -

can he be misunderstanding even himself, or are the many on social media claiming the leading of prophetic authority and insight so as to speak condemnation over him?

From what i can dig up, it seems that the reason for this quote being so incendiary is because many have been searching for years for a smoking gun that would prove his being 'unclean'

that had been only suspected by his close association with Pastor T.D. @bishopjakes on this same subject. The battle in question has had volleys in both directions;

the current flaying is taking place by staunch Calvinists, while Furtick has firmly and openly rejected Calvinism for years.

Sticking to Scripture is helpful when excessive rigor and parsimony or excessive boldness and liberalism leaning into audacity with gestures towards vague ecumenism are not yielding answers to root questions of the discernment of spirits.

Here's the quote under examination:
John 16:7 “But very truly I tell you, it is for your good that I am going away.”

Furtick speaking as disciples to explicate their inner monologue: “How could you say something like that Jesus?

..How could you say it is good that you are going away? We followed you. We trusted you and now you are leaving us."

Furtick explaining Christ's saying that it is better for Him to leave the disciples: “No, I am not leaving you, I am changing forms. Up until now I have walked with you, but when I send my spirit I will be in you, so I am not leaving you, I’m just changing locations.”

"Changing forms" is interpreted as code-speak for a doctrine of modalism, set in opposition to trinitarian belief, where G-d is not three persons in one essence, but one person who changes forms between Father, Spirit, and Son.

Christ is pre-existent to His earthly birth in human flesh, having descended from heaven for such humbling, rather than having such as His origin, and so the vernacular easily accomodates the understanding of His having changed form from spirit together with the Father,

even before Abraham, to the human body as a baby born to a virgin amidst a mass infanticide, dedicated at the Herodian Temple, and baptized by John (His cousin by flesh) with water and by the Holy Spirit in one event.

But this case from John 16 is in reference to His death, burial, resurrection, and ascension to Heaven after His cousin has been murdered by a corruption of political authority.

The difficulty is that most discussion about the Trinity is left in mystery and with a lack of definition even by intention - whether out of fear of G-d or out of fear of condemnation as a heretic, the wording is similar -

and so the gatekeeping of Trinitarian doctrine becomes a matter of the unknown that gives credence and glory less to G-d than to the ones who are showing their relative holiness thru vague accusation that carries power through the dry authoritative language of systematic theology

and gives glory to the safety of skepticism and the criticizer rather than the riskiness and vulnerability of laying one's life down for the brethren to

extend mercy in the case that he is in error(with such high emotion to be mixed with fear of self-contamination when there is material corruption involved).

The Holy Trinity is clear enough at the moment of baptism - G-d speaks His approval as Father, the Son is immersed by John the Baptizer in the spirit of the prophet Elijah,

and the Holy Spirit descends like a dove to rest upon the Son -the Son is not understood to be throwing His voice or to be in two places at once.

The reversal takes place at the cross - G-d the Father turns His back because of the Holy Law's requirement, the Son remains obediently affixed to the penalty of those He redeems, and in dying, surrenders His Spirit to the hands of the Father.

Then, in the time of speaking His temporary goodbye (so as to give them hope and remembrance during His departure),

He explains the benefit of the distance (literal, cultural, political, and biological death) to be set between them as He undergoes torture and mockery and judgment at the hands of Jew and Gentile alike.

The benefit is the Holy Spirit, which as just mentioned, He commits to His Father's hands at the cross. This He says before He Himself is yet seated at the Father's right hand, from whence He and the Father send the Comforter to the faithful who remain upon the earth.

The ascension to heaven was physical and literal, in human form just as the birth was. Furtick's reference to Christ living within the saints is not a controversial one, however -

the kingdom of heaven is within, and we are commanded by Him not to go over here nor over there to seek out claimants to the embodiment of His return, despite that being the way that some of the disciples began their journey - "Come and see."

The Apostle Paul similarly testifies to Christ speaking from above in the vision that transformed him, and then living from within as he partakes in his life testimony the sufferings of his own cross to bear, unworthy of Christ's, but faithful in its rootedness.

Back to the original subject of Furtick's statement and modalist theory. For any theory, we must have application - we do not worship a concept,

but the living G-d, Word made flesh, and we are given the test of the spirits in 1 John warning against those who deny Christ's real biological humanity.

First, what is the implication of the ministry of the word speaking of changing forms from dependency upon Christ's physical nearness

to the disciples each being capable of knowing Christ's character and spirit soundly enough that they can live Christ's priestly work of self-denying sacrifice for themselves?

Understanding the need for going past the physical heroism of the discipler to become a discipler oneself is the point of the internalization of the kingdom authority.

Does the fruit bear in greater dependency or greater repentance, is there a multiplication of cross-bearers and the saving of souls?

That's the point of the Word mentioned going forth in the first place - is this the person, and the incident, to make gatekeeping against modalism a hill to die on?

Second, when is the critique of Trinitarian theological testing being applied? Is the key issue Furtick's saying that Christ, by sending His Spirit from the Father to live within the disciples, is changing form from human flesh to spirit in denial of Christ's resurrected body?

Or is he saying the surrender of Spirit on the cross was the seed for the Pentecost that was watered by Christ's walking again at Emmaus and later appearances,

but that during the time of His speaking in John 16, the Spirit resting and overflowing from within Him were effectively the same person?

What is the reading of the Trinitarian who claims heresy has taken place here regarding these events and the fleshed out meaning of Trinitarian doctrine in a living and breathing gospel?

In either case, is anyone's glory being sought after beyond the historical Christ and the continued bloodshed of martyrs each who bear the unworthy crosses that follow His?

Finally, did anyone who heard that message actually understand what was said to mean that Christ, the Father, and the Holy Spirit were the same person? It doesn't seem likely to me.

If there is no clear answer to the question of the timing, interpretation, and sharing of the words he spoke, but only the extrapolation of "changing form" to mean only the sense meant by the high theological theory of modalism and not how it is simply understood by a layman,

then the question is overwrought and ham-fisted, and apt judgment in the issue remains a matter between Steven Furtick's soul and G-d. Castigating him for heresy on this particular issue, then, is dangerous, harmful, and at the very best a premature assumption still.

Why not just ask him plainly whether he thinks G-d is a ventriloquist? Other points sometimes mentioned about allowing women to preach within the church are separate issues (i've agreed with Pastor @johnmacarthur's logic on the subject as Biblically correct),

but all of the issues of applying Scripture for the gatekeeping of heresy could use the temperance & the now-popular warning against gaslighting someone, great or small, since that term is actually a valid critique of Caiaphas & his robe-tearing display to his fellow theologians.