The Renaissance and Scientific Revolution contributed heavily to Enlightenment ideas. The influence of the Reformation was not so great, in fact some reformation thinkers disagreed with Enlightenment ideas.
The Renaissance and Scientific Revolution had challenged the Medieval concept of scholasticism, in which one accepted authority without question. That "authority" included the concept of a geocentric universe, Experimentation was considered dangerous, as it might lead one to error, and error to sin, and sin to damnation. Renaissance thinkers were perhaps the first to question Scholasticism and explore the concept of a rational universe. This idea was further explored during the Scientific Revolution when scholars argued that the entire universe could be proven by mathematical principles. It is here that the first conflict with Reformation thinkers became apparent. In response to Copernicus' theory that the solar system was heliocentric, Martin Luther called Copernicus:
the new astrologer who wants to prove that the earth moves and goes round….This fool wants to turn the whole art of astronomy upside down
In summary, the Enlightenment is normally considered by scholars to be the natural conclusion of the Renaissance, since both were secular in their approaches. The only explanations accepted were those which were reasonable and "worldly." It was further a continuation of a process which began with the Scientific Revolution. From that revolution, a new way of thinking about science, nature, and humanity had developed. That way of thinking was the nativity of the Enlightenment.