No man can serve two masters. Matt. 6:24.
Obedience can come only by faith, first of all, because of the nature of mankind. We are sinners. We will be sinners until Jesus comes, and sinners cannot produce obedience. Second, obedience can come only by faith; because since we are sinners and cannot produce obedience apart from God, all we can do is give up ever hoping to produce any real obedience. The only thing we can do is surrender, give up on ourselves, submitting totally to the control of Jesus Christ.
What does it mean to be controlled by God? I used to think that there were three choices as to who could be in control of my life. I thought that we could either be under the control of God, or we could be under the control of Satan, or we could be in charge of ourselves and run our own lives. There are many young people, teen-agers especially, who would like the option of being able to be in control of themselves. They have experienced the thrill of breaking from the nest, and are eager to do their own thing.
It comes as a surprise to discover that there's no such thing as being in control of ourselves. We are either under the control of one or the other of two powers--that's all. The only control we have is to choose which power is going to control us. Had it not been for the cross, we would have been hopelessly under the devil's control, with no other option. But Jesus at the cross made it possible for God to give us another choice--the choice to come under His control.
Being under the control of Satan brings the most abject slavery. Choosing to come under God's control brings the greatest freedom. But it's still control. "Know ye not, that to whomye yield yourselves servants to obey, his servants ye are to whom ye obey; whether of sin unto death, or of obedience unto righteousness. But God be thanked, that ye were the servants of sin, but ye have obeyed from the heart that form of doctrine which was delivered unto you. Being then made free from sin, ye became the servants of righteousness" (Rom. 6:16-18). The question here is whether I'm a servant of sin and Satan or a servant of Jesus. There is no other choice. Jesus Himself talked about only two masters, and you can't serve both. It's always one or the other. The choice is open to each of us today to choose who will control our lives.