Actually, the scriptural document detailing the Assumption, De Obitu S. Dominae, was declared apocryphal by the canonists. Doubtless that was not for the Assumption, but for some other proposition considered erroneous. Records show that the Assumption remained a reputable belief.
Well, let’s look at a couple of items of interest from the Catholic Church.
The belief in the corporeal assumption of Mary is founded on the apocryphal treatise De Obitu S. Dominae, bearing the name of St. John, which belongs however to the fourth or fifth century. [http://www.newadvent.org/cathen/02006b.htm]
So even the Catholic Church admits that the belief for the assumption of Mary comes from a dubious work. That should give a great feeling of assurance in what that organization believes and even proclaims to be something that must be believed.
Then we have this from the Catholic Church.
St. Juvenal, Bishop of Jerusalem, at the Council of Chalcedon (451), made known to the Emperor Marcian and Pulcheria, who wished to possess the body of the Mother of God, that Mary died in the presence of all the Apostles, but that her tomb, when opened, upon the request of St. Thomas, was found empty; wherefrom the Apostles concluded that the body was taken up to heaven.[ http://www.newadvent.org/cathen/02006b.htm]
So the RCC claims that all the Apostles were present at her death but not one of them wrote about it even though it is so central to beliefs of the RCC. We are to believe that the Apostles “concluded” that her body was taken to heaven but not one of them thought such an important event should be recorded.
How gullible must one be to fall for such a cult? And then have the audacity to proclaim as heretics those who hold to scripture only as the source for all truth.