Nirvana (Nibbana) is the mind perfectly cleansed of all traces of greed, hatred & self-delusion, which includes fear. It is also the completeness of virtuous social qualities such as love & compassion. Thus Buddha said things such as:
1. Nirvana is supreme
2. There is nothing further for this world
I trust many Christians & other religious have reached great spiritual heights, particularly great love & fearlessness.
I am just pointing out the Buddha mind is the pinnacle of evolution & it can certainly be matched but not surpassed.
