Why does St. Clement of Alexandria criticize paganism?

He criticizes it because it corrupts human freedom in one way or another. For example, he speaks of Orpheus and how through his songs, he corrupted the “noble freedom of those who lived as free citizens under heaven” and enslaved people to demonic magic and prattling.¹⁰⁷⁰ St. Clement allegorically interprets Christ’s invitation to every believer to leave his father and mother to follow Him; for the believer leaves the world behind, namely his mother, and abandons his father, namely the civil laws that are against the faith, for the sake of God’s friendship and to be at the right-hand of the altar.¹⁰⁷¹ Thus, he enjoys the free will to choose whatever is best for him.

1067 St. John Cassian, The Conferences 4.19 (NPNF II/11:336–337). 1068 St. Anthony the Great, “On the Character of Men and the Virtuous Life: One Hundred and Seventy Texts,” in The Philokalia: The Complete Text, Volume I . Trans., G. E. H. Palmer et al., eds., Nicodemus of the Holy Mountain, and Makarios of Corinth (Farrar, Straus and Giroux, 1979): p. 332.

1069 St. Anthony the Great, “On the Character of Men and the Virtuous Life: One Hundred and Seventy Texts,” in The Philokalia: The Complete Text, Volume I . Trans., G. E. H. Palmer et al., eds., Nicodemus of the Holy Mountain, and Makarios of Corinth (Farrar, Straus and Giroux, 1979): p. 337.

1070 St. Clement of Alexandria, Exhortation to the Heathen 3 (ANF 2:183–184).

1071 Cf. St. Clement of Alexandria, The Stromata, or Miscellanies 4.15 (ANF 2:426–427).