I’m answering this question in terms of knowing not being something of the intellect based solely in sense consciousness, rather it is a knowing of the deeper wisdom of the heart.
This question reminds me of the saying “you must believe it first, in order to see it.” In the same way, we can absolutely pray in order to know that all is well. Prayer can lift us out of the perceived limitations we face, and into a dimension of consciousness that transcends those boundaries. We can access a much deeper wisdom-based knowing by turning within through prayer. Prayer can help us loosen error thoughts and subconscious commitments to outer appearances and judgments.
In terms of knowing, what is it that we want to know? I would say that is knowing our true spiritual identity, and that the essence and presence of God is right here, right now, and we are inseparable from that.
While I believe that some of us just know spiritual truth—perhaps the prefrontal cortex is not so dictatorially developed—I do see prayer and meditation as THE path to knowing. It is all about quieting the mind, turning within, and spending time in the silence to allow the truth of what is and has always been to be uncovered. The power to know the deepest truth of spirit is within each of us, waiting to be accessed, and can not be gained from any external source.
When we access this awareness through prayer, we can call it enlightenment. I love that Unity recognizes enlightenment and the spiritual path not as a one way ticket, but it is a round trip. We come back and integrate this consciousness and awareness of Oneness into the sense realm in which we have our human experience (including our ego and intellect)—then we get to walk in the world as did our Way shower, Jesus Christ.
Peace of the Universe 