Submit to ... God - so ye shall be among “the humble,” Jam 4:6; also Jam 4:10; 1Pe 5:6.
Resist ... devil - Under his banner pride and envy are enlisted in the world; resist his temptations to these. Faith, humble prayers, and heavenly wisdom, are the weapons of resistance. The language is taken from warfare. “Submit” as a good soldier puts himself in complete subjection to his captain. “Resist,” stand bravely against.
he will flee - Translate, “he shall flee.” For it is a promise of God, not a mere assurance from man to man [Alford]. He shall flee worsted as he did from Christ.