First up is this article on the fact that Yosef is not a Christian and how and why its damaging to the real churches in Iran:
"Youcef Nadarkhani has been reported in both the secular and Christian media and periodicals to be under a death sentence for his conversion from Islam to evangelical Christianity. He was arrested on 12th October 2009, in the city of Rasht in the northern part of Iran, where he had been the pastor of the underground church there. He is reported to be the evangelical pastor of “the Church of Iran”. However, what might come as a shock to many evangelical believers is that "Pastor" Nadarkhani is actually one of the leaders in a growing cult in Iran, which is linked with the Oneness Pentecostalism (Jesus Only) cult, which is non-Trinitarian, believes in baptismal regeneration, and is very closely linked and supported by the United Pentecostal Churches outside of Iran. They greatly admire and follow the teachings of an American preacher, William M. Branham, who claimed to be the last of God's prophets on earth, that the doctrine of the Trinity is from the devil, and only those who are baptised in Jesus' name are saved...
For the past number of years, these anti-Trinitarian cult teachers, including Youcef Nadarkhani have been militant in their proselytising and recruiting of individuals, especially in Rasht and Shiraz. Pastor [name withheld for security] (as well as many other of our Christian contacts), who is the evangelical pastor of a truly evangelical church in Rasht, confirmed to us personally that Mr Nadarkhani, and his colleagues reject all other protestant churches as not being true churches. Moreover they teach, other classic errors of the Jesus Only cult, including speaking in tongues as the main sign of true salvation. In a recent TV interview by Press TV, Mr Nadarkhani confirmed some of his doctrinal beliefs, which clearly show that he is not an evangelical Christian, even though he speaks about trusting Jesus Christ. He clearly denies the evangelical doctrine of the Trinity."
Here's the video with Yosef saying he is not a Trinitarian.
This is probably why the other churches are not considering them within the faith, and rightly so (more links on this below).
Here is a like-minded website that admits the non-Trinitarian view of the Church of Iran. Wrongly Jason Demars says its not modalist, but it definitely is.
Here and here it is also stated that the Church of Iran is not Trinitarian and that others consider it more of a cult.
This could be 1) showing the world how intolerant REAL Islam is of non-Islamic religions, and 2) God sifting those who claim to be HIS but are not.
2Co 11:3 But I am afraid that, as the serpent deceived Eve by his craftiness, your minds will be led astray from the simplicity and purity of devotion to Christ. 4 For if one comes and preaches another Jesus whom we have not preached, or you receive a different spirit which you have not received, or a different gospel which you have not accepted, you bear this beautifully.
Gal. 1: 6 I am astonished that you are so quickly deserting the one who called you by the grace of Christ and are turning to a different gospel— 7 which is really no gospel at all. Evidently some people are throwing you into confusion and are trying to pervert the gospel of Christ. 8 But even if we or an angel from heaven should preach a gospel other than the one we preached to you, let him be eternally condemned! 9 As we have already said, so now I say again: If anybody is preaching to you a gospel other than what you accepted, let him be eternally condemned! 10 Am I now trying to win the approval of men, or of God? Or am I trying to please men? If I were still trying to please men, I would not be a servant of Christ.