There are but two religions in the world – the religion of the Law and the religion of the Gospel.
In the religion of the Law, you work your way up to God. In the religion of the Gospel, God comes down to you.
In the religion of the Law, you earn God’s favour; in the religion of the Gospel, God’s favour is undeserved. We call it “grace.”
In the religion of the Law, you justify yourself; in the religion of the Gospel, God justifies you.
There are many religions of the Law that go by many names with many gods and many ways to those many gods. You may worship a false god or you may worship the true God falsely, it does not matter when it comes to the religion of the Law. The religion of the Law brings death and destruction whether you worship a false god or the true God according to the Law. A natural born, dyed in the wool, sinner cannot be justified by the Law. The Law kills; the commandment condemns. The religion of the Law, though it promises grace and everyblessing to all who keep the commandments, ultimately fails to deliver because there is no one who keeps the commandments. Not you, not me, not anyone.
There is one religion of the Gospel, the one that approaches God not by works of the law but by faith in Jesus Christ, not on the basis of what we do, but on the basis of what Jesus has done for us, not with commandment keeping but with promise believing.
There is only one religion that works this way. It’s called Christianity, though admittedly many Christians slip into the religion of the Law and make forgiveness, life, and salvation something we do or earn. Even if our part in it is a tiny part, just a little spark of something good, a little leaning in the right direction, a little helping God along by making the right decision, it’s the religion of the Law and not the Gospel.
“Yet to all who received Him, to those who believed in His name, He gave the right to become children of God— children born not of natural descent, nor of human decision or a husband’s will, but born of God.” (John 1: 12, 13)
No matter how religious you may be, the Law will always accuse you, always humble you, always shut your mouth, amplify your sin, and ultimately kill you. That’s what the Law does to sinners.
If you attempt to worship God according the Law, to earn His favour with your commandment keeping, your piety, your good works, your religion, you will not be justified but condemned. Even if you worship the true God, it doesn’t matter, because to worship God in the way of the Law is to treat God like an idol. Not good.
That means it is pointless to argue whether Jews or Muslims worship the true God or not. It doesn’t matter. They worship according to the religion of the Law, seeking the righteousness of God through works rather than trust. It also means that even those who call themselves Christians, and that includes you and me, can slip into the same religion whenever we seek to earn God’s favour by way of the Law instead of the Gospel, by what we do instead of what God in Christ has done for us.
“Where, then, is boasting? It is excluded. On what principle? On that of observing the law? No, but on that of faith. For we maintain that a man is justified by faith apart from observing the law.” (Romans 3:27, 28)
“For it is by grace you have been saved, through faith—and this not from yourselves, it is the gift of God— not by works, so that no one can boast.” (Ephesians 2:8,9)
God justifies the ungodly, not the already godly. He forgives sinners, not saints. He acquits the guilty, not the innocent. You have been baptized into the religion of the Gospel. You have been declared dead to sin and dead to the Law and its religion.
And in this religion of the Gospel, of trust in the free promise of life in Christ, you receive the promise of eternal life!