Is Obedience Necessary for Eternal Life?

There is a strong bias afoot in modern Christianity that eternal life is “by grace alone” or “by faith alone” or “by Christ alone”, and so forth. But when the apostles and prophets used such words as “belief”, for example, did they have in mind some virtue that is wholly detached from obedience? Did they have in mind something apart from human behavior?
No, they did not  The following passages make it pretty clear that they thought about Christianity in a different way than do many churches today. You’ll see that obedience was an integral and necessary part of the faith that was taught at that time—and not separate from it.  Each passage below is followed by a note.
John 3:36 Whoever believes in the Son has eternal life; whoever does not obey the Son shall not see life, but the wrath of God remains on him.

Note in the passage above that there is a connection between belief and obedience. How did Jesus and his apostles and prophets view this connection?
Acts 5:29 But Peter and the apostles answered, “We must obey God rather than men.
Peter does not speak of obedience as optional, but as imperative.  That is in stark contrast to many today who view it as a nice-to-have.
Acts 5:32 And we are witnesses to these things, and so is the Holy Spirit, whom God has given to those who obey him.
No mention is made here that the indwelling Holy Spirit was ever given to the disobedient.  I know of no passage that says that it was.  Even so, the Holy Spirit was that “deposit” that guaranteed their inheritance in heaven. (See Ephesians 1)
Acts 7:39 Our fathers refused to obey him, but thrust him aside, and in their hearts they turned to Egypt,
This is a reference to the “rebellion”, in which some argue that the only failure was one of belief, and not of behavior or merit. Yet here it is described by the inspired pen as a matter of disobedience.
Romans 1:5 through whom we have received grace and apostleship to bring about the obedience of faith for the sake of his name among all the nations,
Here obedience and faith are so tightly joined as to make it impossible to determine whether the apostle considered one to be more important than the other.
Romans 2:5 But because of your hard and impenitent heart you are storing up wrath for yourself on the day of wrath when God’s righteous judgment will be revealed. 6 He will render to each one according to his works: 7 to those who by patience in well-doing seek for glory and honor and immortality, he will give eternal life; 8 but for those who are self-seeking[a] and do not obey the truth, but obey unrighteousness, there will be wrath and fury.
Here the disobedient are doomed to wrath, and not to eternal life.  How, then could a disobedient Christian have escaped that wrath without repenting of the disobedience?
Romans 5:19 For as by the one man’s disobedience the many were made sinners, so by the one man’s obedience the many will be made righteous.
It is very instructive that it does not say “faith” here, but “obedience”. By imitating Adam’s disobedience, many were made sinners, but by imitating Jesus’ obedience, many would be made righteous.
Romans 6:16 Do you not know that if you present yourselves to anyone as obedient slaves, you are slaves of the one whom you obey, either of sin, which leads to death, or of obedience, which leads to righteousness?
Had he said “faith” here, no one would bat an eye. But he says “obedience” instead, showing that he does not have the disdain for the concept that many today seem to have.
Romans 10:16 But they have not all obeyed the gospel. For Isaiah says, “Lord, who has believed what he has heard from us?”
Another strong tie between obedience and faith is made here.  Who are we to untie it?
Romans 15:18 For I will not venture to speak of anything except what Christ has accomplished through me to bring the Gentiles to obedience.
Again, had he written here, “to faith”, no one would have the least trouble with it, but it says “to obedience”, which many try to claim is something different from faith—something secondary in its value, and not primary.)
Romans 16:but has now been disclosed and through the prophetic writings has been made known to all nations, according to the command of the eternal God, to bring about the obedience of faith
There’s that phrase again, linking obedience and faith together, as if it were impossible to have faith without having obedience, too.
2 Corinthians 10:5 We destroy arguments and every lofty opinion raised against the knowledge of God, and take every thought captive to obey Christ,
Paul speaks of his own ministry team here, making it clear that their standard of conduct was that even their THOUGHTS were to be obedient. And not just some of their thoughts, but every thought.
2 Corinthians 10: 6 being ready to punish every disobedience, when your obedience is complete.
Here Paul talks about how acts of disobedience were punishable—which is a surprise to many Christians today. Further, he shows that they were expected to be maturing in their obedience.  This was non-negotiable in their culture, even though it is generally considered optional among the churches of today.
Galatians 1:6 For in Christ Jesus neither circumcision nor uncircumcision counts for anything, but only faith working through love. 7 You were running well. Who hindered you from obeying the truth?
After telling them that only “faith working through love” counts, he shows that whatever had gone wrong in their case was a matter of DISOBEDIENCE. Again, he has tied faith and obedience together quite strongly.
2 Thessalonians 1:7b …when the Lord Jesus is revealed from heaven with his mighty angels 8 in flaming fire, inflicting vengeance on those who do not know God and on those who do not obey the gospel of our Lord Jesus. 9 They will suffer the punishment of eternal destruction, away from the presence of the Lord and from the glory of his might, 10 when he comes on that day to be glorified in his saints, and to be marveled at among all who have believed, because our testimony to you was believed.
Here, a strong opposite relationship is recognized between those who believe and those who do not obey. How can we, then, drive a wedge between belief and obedience, as if the kind of belief that Paul was talking about was not permanently tied to obedience?
2 Thessalonians 3:14 If anyone does not obey what we say in this letter, take note of that person, and have nothing to do with him, that he may be ashamed.
Does this shunning reflect how God also felt about the disobedient? Would he accept them himself, and yet tell his other children to shun them?  That is hard to fathom.
Hebrews 5:9 And being made perfect, he became the source of eternal salvation to all who obey him,
Again, had the writer said “trust” or “have faith in”, nobody would think it strange. But instead, he wrote “obey”, showing that they thought of things differently from how many moderns do.
Hebrews 11:8 By faith Abraham obeyed when he was called to go out to a place that he was to receive as an inheritance. And he went out, not knowing where he was going.
Here we see that it was the faith through or by which Abraham obeyed. His reliance upon God was necessary for him to obey what he was being told, so he continued to rely, going wherever he was sent.
1 Peter 1:22 Having purified your souls by your obedience to the truth for a sincere brotherly love, love one another earnestly from a pure heart,
Here, obedience is shown to be a fundamental necessity even for love and purity. How can one have a sincere love for God without being obedient to God?
1 Peter 4:17 For it is time for judgment to begin at the household of God; and if it begins with us, what will be the outcome for those who do not obey the gospel of God?
Peter identifies the household of God as being comprised of those who obey. Again, had he said “have faith in”, that would fit better with modern ideas. But that’s not what he said. Outside the household of God are the disobedient.
1 John 5:2 By this we know that we love the children of God, when we love God and obey his commandments.
Once again, love and obedience are tied together.
There are many other passages worthy of consideration in relation to this question of the necessity of obedience, but the ones above are more than sufficient to demonstrate that Jesus and his apostles and prophets held a different view of obedience than is popular among the churches today.  It is very troubling to watch people try to drive a wedge between faith/belief and obedience/behavior.