How Moojan Momen misleads the less-informed reader?

Shoghi Effendi insisted that new Baha’is should leave their churches (and mosques and synagogues), indicated that believers should not celebrate Christmas and other religious festivals, and inveighed against the various rituals and the clergy of other faiths. Momen knows all this (he has written books on world religions and even one on Buddhism), so why does he pretend that converts do not have to reject any of their old religious beliefs? Simply, I believe, because the Baha’i doctrine of a single revelation that has progressed from one ‘Manifestation’ to the next entails the assumption that all religions are basically the same, even when they are not. This is misleading for the less-informed reader...

(Making the invisible visible: introductory books on the Baha'i religion, Denis MacEoin)