Paul reiterates the fact that the Gospel he is preaching is not of man five times in chapter one! FIVE! (not sent from man, nor the agency of man ... is not according to man ... not received it from man ... did not consult with flesh and blood). Seems like he was trying to get the point across to the church of Galatia that the focus is on the spiritual, not the physical... on God, not man.

He continues on in the letter to drive home this idea as he show the contrasting views on law versus grace, works versus faith, living by flesh versus walking in the Spirit, etc.

Galatians 1:1, Galatians 1:11-12 and Galatians 1:16