Aquinas addressed the issue of what we believe and why we retain this belief.
He is careful to distinguish between these two issues. He does so by differentiating these different perspectives or questions by distinguishing between his role as a philosopher and his role as a theologian.
As a theologian Aquinas articulates and defends the revelation of the history of the world, the future of the world, and the salvation of the world.
As a philosopher, Aquinas understands his job to be clarifying what the world is like using reason and rationality unaided by divine revelation.
Interestingly, Aquinas admits that philosophical arguments would lead him to believe that the world has always existed and actually had no beginning point. In his conclusion as a philosopher the world may have gone on forever and he contends that this is a reasonable conclusion.
However, Aquinas also believed that unaided human reason couldn't prove that the world did or did not have a beginning. If we were to ask Aquinas why he believed that the world had a beginning, he would as a theologian have assigned this believed to the fact that the first word of the Bible states that the world had just such a creative beginning.
In this progression of thought, we observe the different roles of Aquinas as a philosopher and a theologian.
In addition, in his work entitled Summa contra Gentiles, Aquinas evidences his philosophical role. The work is aimed at individuals who are not Christian, but who are Islamic or Jewish or even atheistic.
His aim is to present the non-Christian with purely human reasons for believing there is a God.
However, in his Summa Theologia, Aquinas is targeting a Christian audience that accepts scripture. While in this work Aquinas does make use of philosophical rationality and reflection, he does not primarily do so as with Summa contra Gentiles.
