The Duty for Rational Discernment of Divine Revelation is the first obligation we have towards God once we choose to believe in His existence. We were created as thinking, rational beings, and God expects us to use our intellect to attempt to understand and determine how He wants us to conduct our lives.
Rational discernment consists of study, reading, prayer, discussion, and fellowship. We cannot expect to know God's will in its entirety -- because we, as humans, are limited in our ability to comprehend Him. We can, however, understand parts of His will, and we must attempt to do so in good faith.
This duty is especially significant for believers in a 21st Century world of instant communications. Thomas Aquinas, writing in the 13th Century, felt that man was too limited in intellectual capability to undertake such a project, and must simply accept Divine Revelation as such. Eight centuries later, the ideas of Aquinas remain powerful, yet not sufficiently relevant to our current world.
The concept of The Duty for Rational Discernment of Divine Revelation has arisen in the context of the new book I am co-authoring with Dr. Rashid Ahmad, Abrahamic Small Groups.
Muslims, Christians, and Jews, for the most part, have little difficulty in agreeing that there is One True God. The Argument from Design is as powerful to Muslims as it is to Christians.
The problem comes in discerning what the will of that One True God is.