You brought up a very worthy topic by sharing of that experience which has been subject of much discussion among philosophers of Illumanationist tradition.
Those feelings are regarded in Illuminationist and indian philosophies as indications of an awakened spiritual self or spiritual illumination. It is only through illumination from above that real knowledge of truth is attained, which is a knowledge acquired by an internal unity with the object of knowledge rather than logical/conceptual understanding. It is also a knowledge that purifies man's ego from immoral sentiments and illnesses or requires them as prerequisite. At its higher development phases, it can produce feelings of internal expansion, restlessness and love yet which that still stabilize and tranquilizes man against external difficulties, mental anxieties and doubt. World-renowned Persian sufi poets such as Hafiz and Rumi (Molavi) composed their mystical poems in such states of spiritual ecstasy.
Yoga practices are also meant to awaken these similar spiritual emotions within human self. The feelings are attributed to a transcendental universal force dormant in all human beings, the Kundalini.
This phenomena has been studied or highlighted as a form of Divinely-aided knowledge by the philosophers of the Illuminationist tradition, such as Plotinus and Saint Augustine. Al-Farabi the 10th century persian muslim philosopher, for the first time, integrated this theory of knowledge into his Aristotelian metaphysics. He argued that all forms of philosophical knowledge emanate from a supernatural being that he named "the Agent Intellect" ("Active -" and "Creative Intellect" are other translation variations). He established parallels between this spiritual source and the Gabriel, an archangel that is believed to inspire Prophets.
The belief in the Active Intellect was reserved by later philosophers of the Peripatetic tradition such as Avicenna. But due to the conceptual/logical method of Peripatetic philosophy, the knowledge granted by the Agent Intellect is often viewed as conceptual and theoretical rather than spiritual.
Suhrewardi a 12th century persian philosopher reconstructed the Illuminationist philosophy into an emanationist cosmology expressed in metaphorical language where beings are compared to beams of light all emanating from a Light of Lights (God). To realize the realm of lights or, higher, the Light of Lights (God), man should liberate itself from the shackles of dim, mundane, material world. Here too, effective knowledge is attained through internal realization of heavenly lights rather than a mere conceptual understanding of them.
Much later in 16th century, the genius Mulla Sadra (Sadr ul-Mote'allehin) the latest most prominent Persian mystic and philosopher, based on his innovative ontological theory that existence is a gradient of most intense level to the least intense level, and that knowledge emanates from the intense levels of existence hierarchy (namely the realm of incorporeal intellects), proved that it is a unity (rather than a mere connection) by the object of knowledge (the Active Intellect) that produces spiritual enlightenment, which is superior to conceptual knowledge which is yielded through only a remote connection with the Active Intellect. Based on his existentially gradient cosmology, the feelings associated with such enlightenment are explained by the higher intensity of it compared to the conceptual/logical knowledge. (A comparative study of Suhrewardi and Mulla Sadra's theory of Knowledge available here)
And with respect to your experience, the feeling of peace and joy indicates that your mere "belief" in God has found its corresponding reference point in heavens through an actual unity with the object of faith.