Chazal tell us that Avraham Avinu, already from a young age was impressed by the Perfection in Creation and realised that there must be a Higher force orchestrating the wonderous ways of the world.
The Steipler Gaon ztz"l, in his sefer בִּרְכַּת פֶּרֶץ, points out that the name אַבְרָם, as אַבְרָהָם was initially called, is an acronym for רְאוּ מִי בָּרָא אֵלֶּה, see Who created all this. This signifies that the mission of recognizing Hashem through studying Creation, was אַבְרָהָם's essence.
These words come from the verse (ישעי' מ כו) "שְׂאוּ מָרוֹם עֵינֵיכֶם וּרְאוּ מִי - בָרָא אֵלֶּה" - Lift up your eyes on high and see, Who created these. Yeshaya haNavi is encouraging Klal Yisrael to recognize Hashem's Power and infinite wisdom, by viewing the celestial bodies. We are to ponder the miraculous work of Hashem and thus gain the vital awareness and appreciation of the Almighty.
Indeed, once he learnt the truth and understood that Hashem created and runs the world, young Avram undertook to spread the word. He travelled from city to town educating the people and fighting vehemently against the untruths of the עֲבֹדָה זָרָה.