"[T]hrough whom we have received grace and apostleship to bring about the obedience of faith for the sake of his name among all the nations" (Romans 1:5, ESV).
"And to whom did he swear that they would not enter his rest, but to those who were disobedient? So we see that they were unable to enter because of unbelief [note correlation]" (Hebrews 3:18-19, ESV).
Here's an anecdote of a believer who had come full-circle (Is he Catholic or Protestant, or Protestant acting like a Catholic?): "I don't believe in the infallibility of Scripture anymore, but I still believe in Jesus as my Lord!"/"O how does he exercise His Lordship?"/ "Through the teachings of the Church!" (Who and what is he obeying?)
In the incident with the rich young ruler who said he had obeyed the commandments; however, the ultimate test was whether he would obey the Lord Himself, according to John MacArthur.
The issue is how does Christ extend His authority over us. We are not to be rule-obsessed like the Pharisees but have a personal link to the Lord, take His yoke of love, and follow His will as the fulfillment of the Law. The Lord exercises His Lordship over us through the Word (as a check on all other authority), through the body of Christ, and through all legitimate authority (even government, unless civil disobedience is called for out of Scriptural reasons), i.e., we cannot say we obey the Lord if we are disobedient to our superiors who have the rule over us (we submit one to another in the love of Christ) and we are rogues, doing their own thing and going their own way, as it were.
Protestants go a step beyond obedience to the authority of the church over them by obeying the Lord as revealed in Scripture via a personal relationship, i.e., knowing the Lord--unlike the rich young ruler who obeyed rules, but not the Lord Himself. Protestant means: I dissent, I disagree, I protest. Protestants are not at the mercy of Church dogma as infallible.
Thinking you can believe without obedience is called easy-believism and its gospel as the no-lordship gospel. "Christ will not save anyone He cannot command," says A.W. Tozer. And will not barter away his claim to lordship and ownership of us. He couldn't be our Savior if He were not Lord of all (cf. Acts 10:36). John MacArthur says "follow Me" refers to unconditional surrender to His lordship. True salvation is free, but it is not cheap, because the Bible doesn't teach "cheap grace" or "cheap peace," the terminology of this heresy if you will, because it cost God everything to redeem us, and He wants all of us in return. "I call it heresy," says A. W. Tozer about this gospel in vogue that dumbs down and domesticates the biblical evangel.
Obedience ultimately also means submission to authority, but some believers are reluctant to follow suit or go there--we are all under authority in the body of Christ and no one is the man in charge, except Christ Himself. We have leaders who are also under authority! "[We] have turned everyone to his own way" (Isaiah 53:6b, ESV).
Since we are creatures and God is our Creator, we owe Him all our obedience by virtue of this alone, whether there is a heaven or not. Even Satan has to obey when commanded and seeks permission for his mischief. Religious people who simply go through the motions and memorize the Dance of the Pious don't please God by their religiosity. God seeks obedience from a "noble and good heart." 1 Samuel 15:22 says: "...Behold, to obey is better than sacrifice, and to hearken than the fat of rams." Dietrich Bonhoeffer, the Lutheran pastor who was executed in a concentration camp by the Nazis for his Christian stand, said eloquently and succinctly: "Only he who believes is obedient, and only he who is obedient believes." They are linked and correlated and go hand in hand in a complementary manner, they can be distinguished but not separated; there is no such class of believer who is perpetually or habitually disobedient--obedience is not an option and the Great Commission is not the Great Suggestion! And we can obey only by the power of Christ working in us (cf. Col. 1:29). God's power is always there to enable us to do His bidding and the power of the Holy Spirit is always on hand to kick in when needed--but we must remember it is His energy not the energy of the flesh. Paul says in Romans 15:18 that he "will not venture to speak of anything except what Christ has accomplished through [him] to bring the Gentiles to obedience by word and deed [actions can speak louder than words and prove our testimony]."
Faith is simply about trust and obedience and learning to walk in them. I love the hymn "Trust and Obey" which stresses this definition of faith. Isaiah 1:19 says in one version, "If you consent and obey you shall eat of the best of the land..," and in the NLT, "If you will only obey me and let me help you, then you will have plenty to eat..," or "If you are willing and obedient, you shall eat of the good of the land... (ESV)." Jesus admonished his disciples in John 14:21: "He who has my commandments and keeps them [obeys], it is he who loves me." Part B of the Great Commission is to "obey" or "observe" His teachings or commandments! We are not done when we make a convert, but must train them as disciples or followers of Christ--they must be learners and students in the school of Christ, in which they have matriculated upon salvation. Jesus' commands are not burdensome according to 1 John 5:3 (compared to the yoke of the Law of Moses), and his burden is light (cf. Matt. 11:29). Only when we submit to His yoke will we find our Sabbath rest.
Jeremiah 4:8 says that Israel didn't "know the rules of the LORD!" What does God require? Deut. 10:12-13 (ESV) says it in a nutshell: "And now, Israel, what does the LORD your God require of you, but to fear the LORD your God, to walk in all his ways, to love him, to serve the LORD your God with all your and with all your soul, and to keep the commandments and statues of the LORD which I am commanding you this day for your good." One of my favorite verses is Micah 6:8 says: "Her has told you, O man, what is good; and what does the LORD require of you but to do justice, and to love kindness, and to walk humbly with your God?" This refers to ethics, brotherly relationships, and fellowship with God. Jesus summed up the deeper requirements of the Law in Matt. 23:23 (ESV) as follows: "...[And] have neglected the weightier matters of the law: justice, and mercy, and faithfulness."
The point is that we cannot do the Law nor fulfill its demands, even though Israel promised to do them rather than plead for mercy in Exodus 24:3 (ESV) as follows: "... All the words that the LORD has spoken we will do [obey again]." The point of the Law is to point out our sin according to Paul in Romans 3:20 in the Phillips translation: "Indeed the straightedge of the law shows us how crooked we really are." Other versions render it: "... [F]or by the law is the knowledge of sin;" "... [Since] through the law comes knowledge of sin." C. S. Lewis aptly said that we don't know how bad we are till we've tried to be good, and we can't be good till we know how bad we are! This is a paradox and worth thinking about, because the closer we get to God, the more we realize our unworthiness and His grace and mercy. Luther said the Law is a hammer that smashes our righteousness and a mirror that shows our faults. Why didn't Israel realize that they couldn't keep the Law? Only Jesus was able to and He did it on our behalf so we don't have to but can have His righteousness imputed to our account and be considered justified (or just as if I'd done it!).
What kind of attitude should we have in obedience? Deut. 26:16 says, "...You shall be careful to do them with all your heart and with all your soul." David says in Psalm 40:8 that he "delights to do [His] will." We do not obey begrudgingly or because we think we have to, but because we want to; we now have a heart of flesh willing to obey God, instead of a heart of stone (Ezekiel 36:26). "... For the love of Christ constrains us" (2 Cor. 5:14). We are not inclined or biased to good anymore and need to be set free, because we are not born free (we are slaves to sin and the sin nature). Our attitude determines our altitude spiritually and we need constant "attitude checks" or "spiritual check-ups." We have the choice to choose our attitude and it should be one of joy in suffering because we are counted worthy. We are not free to disobey at will or our discretion, but free to obey the will of God.
According to John MacArthur, faith is manifest in obedience only. James said, "I will show you my faith by my deeds," while Paul is saying, "I will show you my deeds by faith." We are saved by faith alone, according to the reformers, but not a faith that is alone (that would be antinomianism). Without deeds our faith is suspect! The obedience of faith saves, but works are no substitute for faith, because, even though we are not saved by works, we are not saved without them either. Matthew 7:17 says we shall know them by their fruits. We must bear fruit in keeping with our repentance and so prove our faith (cf. Acts 26:20: "... [Performing] deeds in keeping with their repentance"). Luke 3:8 says, "Bring forth fruits in keeping with your repentance." Obedience is evidence of faith, not its substitute, and God is not against works, just those done in the flesh (cf. Isaiah 64:6). The faith you have is the faith you show is James' key point. Remember, we are judged by our obedience (i.e., our deeds or works per Romans 2:6), not our faith. God is not interested in our achievements or accomplishments, but in our obedience only!
When God tests us, it is for our own good and it is an honor because He trusts us to pass the test and obey Him. You might wonder if you are obedient. Acts 5:32 (ESV) says, "And we are witness to these things, and so is the Holy Spirit, whom God has given to those who obey him." Jesus said, "If any man wills to do His will, he shall know of the doctrine..." (John 7:17). Jesus said in John 17:3 that eternal life is knowing Him; likewise to know Him is to love Him and to love Him is to obey Him--because we now want to do God's will from the heart! Again I reiterate 2 Cor. 5 v. 14: "For the love of Christ constrains [or compels in ESV] us...." Though the believer is capable of disobedience out of failure or because he is human, he possesses a supernatural yearning to obey and please God. As David said in Psalm 40:8 (ESV), "I desire to do your will, my God; your law is with my heart."The ultimate result of knowing Him is to desire to be like Him in sanctification and a growing and living faith. Soli Deo Gloria!