Here are the words of one famous "Heretic" who was a "Believer" in the "Grand heresy of ecumenism". Do you recall who was that "Heretic" (Capitalization intended!!)
“My prayer is not for them alone. I pray also for those who will believe in me through their message, that all of them may be one, Father, just as you are in me and I am in you. May they also be in us so that the world may believe that you have sent me. I have given them the glory that you gave me, that they may be one as we are one— I in them and you in me—so that they may be brought to complete unity. Then the world will know that you sent me and have loved them even as you have loved me."
If you are offended by this, hope you can understand my anguish with all the disturbing I things I had been reading from all sorts of fundamentalist "Christians" especially those who stand firm on the Eastern and Oriental Orthodox Schisms including clergy, monks, and elders!