Paladins are secular in the sense of not ordained. They generally have a strong interest in religion, but they do not need to support any single religion or number of religions to receive their powers.
They do not need to draw their powers from any single or group of divinities any more than a Cleric does. Indeed, prayer is quite optional for both, as meditation will apparently suffice.
Secular definition B has two clauses: deities or religion. I am arguing a Paladin does not need to be concerned with deities to receive his power, but that does not prohibit spirituality or concern with religion.