[3:149-150] O you who believe, if you obey the disbelievers, they will make you turn back on your heels, and you will revert as losers. * Nay, but God is your Protector, and He is the best of helpers.
It means that if you obey the adversaries, they will pull you into their states and cast you into their darknesses. Nay, God is your Protector, your Helper, the One who aids you, Your Master, and the One who sets your affairs aright. And He is the best of helpers because He aids you against your lower selves, protecting you from their evil. Anyone other than Him adds to your afflictions when they help you because they aid your lower selves against you. And He is the best of helpers because anyone other than Him bestows a favor in helping you, while He rewards you for your asking for His help.
It is said that you need to give something to anyone from whom you have asked for help from your valued things, whether he has helped you or not. But when you ask Him (s) for help, He gives you every kindness, and takes no pleasure in not helping you.