“Seek ye first the kingdom of God,” Jesus famously said (Mat.6:33).
He made it clear that “My kingdom is not of this world.” (John 18:36).
In that case, where is it? “The Kingdom of God is within you,” Jesus simply explained (Luke 17:21).
He then promised to Peter: “I will give you the keys of the kingdom of heaven” (Mat 16:19)
The apostles, including Peter, as we read in the Autobiography of a Yogi, received Kriya Yoga. In fact, the “keys of the kingdom of heaven” according to Yogananda, refer to inner techniques, especially to Kriya Yoga, which Jesus taught, and which opens the inner doors: the chakras, the deep spine, and the Christ center between the eyebrows, where “the kingdom of heaven” exists in man.
That meditative, personal, inner key to try knowledge, that mystical key to the kingdom of God, however, has always been rejected by “churchianity”, which openly declares that “In Christianity, the keys are an office and power given by Christ to the Church for binding and loosing sins.”
Jesus accused them heavily: “Woe unto you, lawyers! for ye have taken away the key of knowledge: ye entered not in, and them that were entering in ye hindered.” (Luke 11:52)
In time they will all learn to enter in, if indeed the “kingdom of God is within”.