The conscious life of all men is apparitional and illusive.
The Manicheans' answer to such arguments was that miracles worked by Christ and the Apostles in the material world were only apparitional and not real, while those of the Old Testament were satanic.
These beings were supposed to possess the power, whilst they continued to live in heaven, of appearing on earth in a Nirmanakaya, or apparitional body.
Thus the way was opened for other apparitional Buddhas, and different sects take different ones as the objects of faith and worship. Moreover, our true nature is also Buddha.