Paulo never said: ” I am unable to ….. ..” He always said that he would try to do – he believed that god would help him and give him the strenghts to do what Jesus wants him to do. – When I feel strong, I am weak, and when I am weak, I am strong ! – For everything I am strong in God, all my strenghts come from Him, even when the devil wants to frustrate. God did not defeat the devil in his position of god, but in his position of being human. Showing power as a human he wants us to show, that every man can defeat the devil – when being empowered from god. The devil is angry because he can do nothing against the empowered man.
The church is the inheritor of the strenghts of god. See: Romans: 11
11 Again I ask: did they stumble so as to fall beyond recovery? Not at all! Rather, because of their transgression, salvation has come to the Gentiles to make Israel envious. 12 But if their transgression means riches for the world, and their loss means riches for the Gentiles, how much greater riches will their full inclusion bring!
13 I am talking to you Gentiles. Inasmuch as I am the apostle to the Gentiles, I take pride in my ministry 14 in the hope that I may somehow arouse my own people to envy and save some of them. 15 For if their rejection brought reconciliation to the world, what will their acceptance be but life from the dead? 16 If the part of the dough offered as firstfruits is holy, then the whole batch is holy; if the root is holy, so are the branches.
17 If some of the branches have been broken off, and you, though a wild olive shoot, have been grafted in among the others and now share in the nourishing sap from the olive root, 18 do not consider yourself to be superior to those other branches. If you do, consider this: you do not support the root, but the root supports you. 19 You will say then, ‘Branches were broken off so that I could be grafted in.’ 20 Granted. But they were broken off because of unbelief, and you stand by faith. Do not be arrogant, but tremble. 21 For if God did not spare the natural branches, he will not spare you either.
22 Consider therefore the kindness and sternness of God: sternness to those who fell, but kindness to you, provided that you continue in his kindness. Otherwise, you also will be cut off. 23 And if they do not persist in unbelief, they will be grafted in, for God is able to graft them in again. 24 After all, if you were cut out of an olive tree that is wild by nature, and contrary to nature were grafted into a cultivated olive tree, how much more readily will these, the natural branches, be grafted into their own olive tree!