King Charles the First was the King of England who, after the English Civil War II, was beheaded for treason against the Parliament. He was a firm advocate for the Episcopal nature of the Clergy and High Church Anglicanism. Yet, King Charles unfortunately believed in Arminianism. Arminianism teaches atleast two things that are not in conformity with either the Catholic or Orthodox faith. These things are total depravity and penal substitution.
The Church does not teach total depravity, this was a Calvinistic perspective and has been refuted by both the Orthodox and Roman Churches. The fact is that both agree that the image of God was obscured in man, but was not totally obliterated as is taught in Calvinism. Arminianism continues this thought and it is erroneous. God did not abandon man, he gave them clothes for themselves and promised a messiah (see Genesis 3). The Catechism of St. Philaret of Moscow teaches us this as well on the sections concerning the fall of man.
Also the Orthodox and Roman Church do not agree with penal substitution. We do not worship a wrathful God who desires to punish all who sin and so we must give him a sacrifice of satisfaction in order to appease this wrathful God. This has never been the teaching and in fact it speaks more of pagan thought than true Orthodox Christian teaching. According to St. Nicholas Cabasilas, "Christ broke down the three barriers that separated man from God: the barrier of nature by His Incarnation, the barrier of sin by His death, and the barrier of death by His Resurrection." For this Christ died freely for our sins so that we might be able to partake of the divine nature of God through Grace and Adoption. His death, freely given, was meant to overcome death, for "Christ is risen from the dead, and by his death he has trampled death and to those in the tombs he has granted life." (Paschal Hymn of the Byzantine rite). This hymn, used since the earliest times in Christianity and quoted by St. Paul, tells us the purpose of our salvation.
The Orthodox Church cannot celebrate heterodoxy in any form. While the reasons for his martyrdom are worthy of veneration to protect the Sacred Episcopacy, his theological beliefs were not Orthodox, or even Catholic, and therefore we cannot celebrate him on our calendar. The faithful are welcome to have a private devotion to him, but as for public celebrations, these cannot be allowed in this Deanery.