The Apostle Paul
Ephesians 2:2WEB·traditional attribution

in which you once walked according to the course of this world, according to the prince of the power of the air, the spirit who now works in the children of disobedience;

Albert Barnes Presbyterian

Verse 2. Wherein. In which sins, or in the practice of which transgressions. Ye walked. You lived, life being often compared to a journey or a race. . According to the course of this world. In conformity with the customs and manners of the world at large.

John Gill Reformed Baptist

Wherein in time past ye walked,.... Sins and transgressions are a road or path, in which all unconverted sinners walk; and this path is a dark, crooked, and broad one, which leads to destruction and death, and yet is their own way, which they choose, approve of, and delight to walk in; and walking in it denotes a continued series of sinning, an obstinate persisting...

Jamieson-Fausset-Brown Reformed

the course of this world--the career (literally, "the age," compare Gal 1:4), or present system of this world (Co1 2:6, Co1 2:12; Co1 3:18-19, as opposed to "the world to come"): alien from God, and lying in the wicked one (Jo1 5:19). "The age" (which is something more external and ethical) regulates "the world" (which is something more external).