Actually, there is a required obedience during this Mystery Age also.
The obedience of faith - of simply believing...
The obedience of that righteousness which is not of the law, rather, of faith.
Of simply believing that the faith of Christ: the Cross in our stead, was more than sufficient.
Rom. 5: 6-8.
Faith is definitely obeying. However, obedience to the faith doesn't mean you don't have to obeying anything else.
Romans 1:5 King James Bible
By whom we have received grace and apostleship, for obedience to the faith among all nations, for his name:
The old law did not require faith, even though some Jews had it. The old law required works of the law, and those works were the purification works, wherein the person had to clean themselves. There were many purification works that every person had to do to clean themselves.
Since Jesus, no one has to do those works purification works of the law anymore; all one has to do to be made clean now is to believe that Jesus' blood cleans them, of the sins they repent of doing.
That is the not of by works Paul preached. Paul never taught that no one has to obey God anymore. Not of by works means you don't have to clean yourself by getting circumcised and offering the blood of animals, etc.
We still have to obey Jesus by not committing adultery, not lusting, not murdering, not getting angry, not stealing, being content with what we have, caring for family members, not bearing false witness, not gossiping, thinking good thoughts, etc.
Jesus doesn't even save a person and clean them and make his home with them unless they repent of their sins, and have forgiveness in their heart. One must ask for forgiveness to God for your sins and be forgiving to those who sinned and sin against you. You are to call on Jesus to help you, to save you.
During the time of Jesus and then later just the apostles on the earth laying the foundation, the apostles did many things during this special time like no other; God testified to what they said as truth by allowing them to speak in tongues, heal people, and raise the dead. This was the time also when Gentiles where being saved, and they were being saved without searching for God, without looking for God. The apostles came to them and said God has now ordained, appointed your race to be able to be saved too, even though you were enemies to God by not getting circumcised when He commanded, etc. God was offering salvation to the Jews and to the Gentiles before the Gentiles searched for Him; this was during the laying of the foundation. As the foundation was still being laid, and the scriptures being written by letter, the people were hearing the truth, the true gospel, they knew it was true because it was the apostles preaching it and God testified to it by signs and miracles. If someone wanted to be saved, all they had to do is to go into one of the homes where church was being held, or answer their own front door when an apostle or disciple came knocking; or all they had to do was be in the market place, or synagogue, or they could go to Paul's own house.
Now a days if one wants to be saved, they have to weed through all the many false doctrines implanted by Satan and his demons. We have the scriptures now of the old and new. If one wants to find God, a God whom they heard about from other people here and there, they can get a Bible and search for Jesus' teachings and then obey those teaching and be saved.
One learns not to ever give up, give out, or give in, it could take time, and nothing is more important. Jesus himself saves, and we have his words more available. But there is an onslaught of false teachings ready to confuse the one who wants to be saved. There are denominations that will hinder one and succeed with the person never being saved in this life. There will be denominations and false doctrines to confuse and detour the believer with things that are not of God.
We are told to train ourselves, to work out our salvation. We are to stay humble with that forgiving heart, as we ask for forgiveness and repent on our road to the end. We are warned to be careful, to watch our lives and doctrine closely. How does anyone get that we don't have to do anything is a teaching one must recognize as strange and unreasonable.
God's Word is true and life. Never ever is obeying the cause of confusion and condemnation.
If anyone is in the snare of the devil to believe and preach falseness, all one has to do is humble themselves and repent, believe the truth that obeying and repenting is what the Way teaches and leads us.
