Matushka,
I have often asked many ecumenist priests and layman but have so far received no answer: There is no need for lengthy debates or long discussions about any of this.
Because surley those who are of the Church can show everyone Her example without hesitation and without reluctance. Therefore, show me these examples of the Holy Fathers where they instruct us to be in communion with heretics and I will join you tomorrow.
Until such time as this, “they have the churches, but we have the faith” (St. Athanasius), therefore, they "...kick against the goads."