Spiritual authority is one -- not two or four or ten.
The spiritual authority must be eternal because when presenting the eternal Supreme Person God - then that teaching must also be eternal.
Any spiritual/religious teaching coming along in recent history cannot be an authority and it is deemed questionable simply by the fact that it is not eternal.
True religion/spirituality is Sanatana Dharma and not a mundane belief system.
Belief systems are created by speculators and they are like the weather and can change at the whim of the person - and a Muslim can change to Christian and a Christian can change to Muslim or Hindu.
* Sanatana Dharma is the eternal occupation of the living entity and cannot change even after death of the body.
Therefore, sanatana-dharma does not refer to any sectarian process of religion. It is the eternal function of the eternal living entities in relationship with the eternal Supreme Lord. Sanatana-dharma refers, as stated previously, to the eternal occupation of the living entity. Ramanujacarya has explained the word sanatana as "that which has neither beginning nor end," so when we speak of sanatana-dharma, we must take it for granted on the authority of Sri Ramanujacarya that it has neither beginning nor end.
The English word religion is a little different from sanatana-dharma. Religion conveys the idea of faith, and faith may change. One may have faith in a particular process, and he may change this faith and adopt another, but sanatana-dharma refers to that activity which cannot be changed. For instance, liquidity cannot be taken from water, nor can heat be taken from fire. Similarly, the eternal function of the eternal living entity cannot be taken from the living entity. Sanatana-dharma is eternally integral with the living entity.
When we speak of sanatana-dharma, therefore, we must take it for granted on the authority of Sri Ramanujacarya that it has neither beginning nor end. That which has neither end nor beginning must not be sectarian, for it cannot be limited by any boundaries. Those belonging to some sectarian faith will wrongly consider that sanatana-dharma is also sectarian, but if we go deeply into the matter and consider it in the light of modern science, it is possible for us to see that sanatana-dharma is the business of all the people of the world--nay, of all the living entities of the universe.
Non-sanatana religious faith may have some beginning in the annals of human history, but there is no beginning to the history of sanatana-dharma because it remains eternally with the living entities. Insofar as the living entities are concerned, the authoritative sastras state that the living entity has neither birth nor death. In the Gita it is stated that the living entity is never born, and he never dies. He is eternal and indestructible, and he continues to live after the destruction of his temporary material body. In reference to the concept of sanatana-dharma, we must try to understand the concept of religion from the Sanskrit root meaning of the word.
Dharma refers to that which is constantly existing with a particular object. We conclude that there is heat and light along with the fire; without heat and light, there is no meaning to the word fire. Similarly, we must discover the essential part of the living being, that part which is his constant companion. That constant companion is his eternal quality, and that eternal quality is his eternal religion."
The process and method for achieving love of God is called devotional service.
Devotional service will not be presented in this forum - for sadly this forum is not the place to discuss intimate details of God.
Source: the Veda