Fine. Are you saying explicit acceptance of this doctrine and its particular mode of expression is mandatory for all Christians? If so, the answer to my question is "yes".
Yes, acceptance of the uncreated nature of the divine activity is necessary, and also of the idea that it is this uncreated activity (or energy) that is conveyed to man in the holy mysteries (which includes icons), and not some kind of "created" grace, which is an idea that arose only in the West during the 12th and 13th centuries. Only the uncreated can divinize a man.
Now, as far as language is concerned, even St. Gregory himself -- at the councils that took place in the mid-14th century -- indicated that the particular mode of expression was secondary, as long as the theological truth (theologia) of the distinction was made. That being the case, so long as one distinguishes between essence, activity, and person in God (to use the most common Trinitarian expressions in English), there is unity within the Orthodox faith.