On Matt 7:21-23, Jesus is making it clear that doing miracles in His name is not enough, but doing the will of His Father is primary. In order words, and as we always say, the “being” and the “doings” of a born-again Christian are distinguishable but inseparable. We are saved by grace not works, but our works reflect our salvation.
Consider Luke 10:17-20. The 70 were rejoicing because the spirits were subject to them, but Jesus said they shouldn’t be carried away with that, but that their names were written in heaven.
In healing the paralytic man in Luke 5:17-26, Jesus concluded that to heal the man of paralysis is easier than forgiving his sins.(Vs 23-24). Forgiveness of sin is a big thing the Lord Jesus is the one who forgives because He paid the price. Why wouldn’t we follow His instructions?
So to the question about the source of the power used The power they use may or may not have been the power of God, but the mystery remains that God didn’t know them. They are like “Agberos” (meaning Touts in Yoruba language from Nigeria), God can use anything. A so called man of God died recently. He claims to use the power of God, but it is evident it was not the power of God he was using. What this is saying is that your pass to the kingdom is not merit or the miracles you have done in God’s name, but faith in Jesus, and in doing the will of God. Martin Luther over stretched when he use sola fide that we are justified by faith alone. The Scripture he used didn’t have “alone”. The reformation church had to deal with so much chains and shackles tied around salvation in the Catholic church, but we can not make it too simplistic as to ignore the expected life of a believer. After all, you are a Christian because you lived and behaved like Christ.
On the Scripture. Romans 11:29 should be read in the context of the nation of Isreal. Paul made a claim, to conclude that the promise of God to Abraham, Isaac, and Jacob cannot expire, even to their biological children. This only means that God will work it out, so that the nation of Isreal will accept Jesus as their Lord and savior at the end of the day. It does not mean that God will change His rules for their sake. Verse 28 says they are enemies as far as the gospel is concerned but beloved because of the promise made to Abraham. Paul was warning Gentile believers not to be arrogant about being grafted into Christ, but to be humble, and to learn from the experience of the nation of Israel.
I have seen people misuse that Scripture but what Paul was trying to explain is very much similar to the sure mercies of David, that God will always honor His promise, and that God will ensure they accept the Lord Jesus.
See what the Bible says in Jer24:7a: “I will give them a heart to know me, that I’m the Lord.” It means, the gift and calling of God are irrevocable because God will keep His part of divine preservation.
So, Roman 11:29 only supports divine preservation, that those who are genuinely born again will also end up being in right standing with God even if they err, because they will persevere when God corrects them, they will yield to the Holy Spirit, they will not be obstinate. The error being made in the use of that Scripture is to claim it does not matter how they live their lives, God must still deliver. How wrong they are!
So, salvation remains intangible, and it is more doctrinal than something anyone can claim they know it all, but everyone who is truly saved will know in their hearts that they truly saved. I don’t subscribe to juridical justification or alien righteousness the way Martin Luther states it. I agree more with John Wesley that it is possible to live righteously in the hear and now. We can be holy, and we are to be holy, in the hear and now, and not just at the end of the age. A decision to be holy is required, to ensure we are not among the foolish virgins.