The brilliance and wisdom of God is seen in His commanding us to do things which we ought to do, yet which we’re unable to do without His aid. He doesn’t command us in ignorance, unaware of our weakness, but as a way to engage His image in us, and work through us to achieve His purposes.
The fact that God is sovereign, in total control of all things, including us (Ep 1:11), suggests to some that we’re excused from engaging our will in obeying Him, as if to say, “I can’t do anything without Christ anyway (Jn 15:5), so why try?” The error produces passivity, an idleness of the mind and will, which turns out to be the chief basis of demon possession (Ep 4:27); if we don’t resist the devil he will retake in us the ground he used to have (Ep 2:2) and more. (2Ti 2:26)
So, though God is able to sanctify us without engaging our cooperation, He is pleased to work in and through us (Php 2:13), inviting us into our sanctification as participants and enablers, workers together with Him. (2Co 6:1) This doesn’t jeopardize His plan in any sense, it magnifies His omnipotence, but it does reveal something amazing in His agenda.
God is about making us, all of His elect (Mt 24:31), like Himself, training us up as saints such that we think and act like He does. (Ep 5:25-27) He engages His image within us with the very life and mind of Christ to conform us to Christ (Ro 8:29), reincarnating Himself in us (Col 1:27), calling us to act and strive and then working through our will: our willingness and intent to obey Him becomes the vehicle through which He manifests Himself.
God is putting us through the mill down here, through the ringer, so to speak, sort of like boot camp, refining us and sanctifying us, preparing us to rule and reign with Him. (Re 20:4) He will eventually give us unfathomable responsibility – like passing eternal judgement on the angels. (1Co 6:3) He wouldn’t let us participate with Him like this without utmost confidence that we’d call each situation correctly (Ro 15:14), exactly like He would. (1Co 2:16) He is capable of doing this in us, and He will, for His glory. (Ep 2:10)