https://www.christianity.com/god/jesus-christ/the-basics/what-is-christianity-alex-crain.html

There’s much confusion about what Christianity actually is, who can be considered a Christian, and how a person becomes one. Here’s a brief look at how the Bible answers that.

Everyone who asks the question “what is Christianity?” often wonders what the truth is behind something that has been turned difficult to understand by man. As the video above says, Christianity is pretty simple. It’s all about one life, the life of Jesus the Son of God. The Bible teaches that Jesus was God Himself, come to live in His world as a human. Perhaps you’ve never thought about it very much, but the life of Jesus has a tremendous impact on you.

The Bible teaches that because we are sinners by nature and by choice, we have a broken relationship with our Creator. We live out our days seeking fulfillment and meaning in the things that surround us, but the deepest need of the human soul is to be restored to the One who made us. Jesus came to accomplish that restoration.

A true fact about Christianity that sometimes surprises people is that Christianity is Jewish. Jesus demonstrated that He was (and is) the Messiah foretold in the Jewish Scriptures. Christianity is the culmination of Judaism. Jesus (Yeshua) was Himself, Jewish. He was brought up by faithful parents who regularly took Him to synagogue. He observed the Torah perfectly. The last recognized Jewish prophet, John the Baptist, declared that Jesus was the perfect “Lamb of God who takes away the sin of the world” (John 1:29).

The Apostles, the first disciples of Yeshua, were Jewish. After Christ’s resurrection, in Luke 24:1, Jesus showed His followers how all the Hebrew prophets of former times pointed to Him, saying, “Was it not necessary for the Christ to suffer these things and to enter into His glory?” Then beginning with Moses and with all the prophets, He explained to them the things concerning Himself in all the [Hebrew] Scriptures.

The central message of Christianity is that Jesus Christ is God the Son who came to earth to rescue sinners not only from a life of sin but also from eternal damnation in hell. Christians believe that the 66 books of the Bible comprise the inerrant Word of God. As such, they read it, come to know God more deeply by it, stand for and live by its truth.  

Who Can Be a Christian?

At the heart of what it means to be a Christian is justification—that is, being right with God (see Romans 4:20). So, another way of asking “who can be a Christian” is “who can be considered right with God?” John 1:12says that “…as many as received Him [Jesus], to them He gave the right to become children of God, even to those who believe in His name.” In other words, not everyone is automatically a child of God simply because he or she is born into the world.

Galatians 3:1 explains that one becomes a child of God “through faith in Christ Jesus.” A person is not saved by faith. We are saved by Christthe object of faith. In other words, every person who asks to be delivered from sin and trusts Jesus Christ alone for forgiveness will receive God’s forgiveness. Romans 10:9 says, “…if you confess with your mouth the Lord Jesus and believe in your heart that God has raised Him from the dead, you will be saved.” 

This forgiveness also means reception into a new family relationship with God and His people. People who follow Christ gradually take on the character of Jesus. A true child of God will be known by good works, pure thoughts, and godly attitudes. These things are not the grounds for justification. Rather, they serve as evidence of being “born again” by the Spirit of God who lives in all believers (John 3:1Ephesians 1:1) from the very moment of salvation on. 

People question the exclusivity of the Bible’s claim, but it’s not an arrogant stance. The gospel of Jesus Christ is no more arrogant than saying 2 + 2 = 4. Trust in Jesus Christ is the only path to a right relationship with God. Trusting who Christ is and what He did through the cross and resurrection is what we’re called to do. Rejecting that shows disregard for the truth and disrespect to the most loving being in the universe. One of the most common ways people reject Christ is by thinking, “I’m good enough to get into heaven.” But the Bible says no one is good enough to enter heaven (Romans 3:10). Just one sin will keep us out of God’s presence. In Matthew 5:48, Jesus commands: “Be perfect, your heavenly Father is perfect.”

Furthermore, this trusting in Christ is always accompanied by repentance, according to the Bible. Repentance means turning away from sin and submitting to Jesus Christ as the ruler (Lord) of one’s life. Intellectual assent to the Bible’s truth without a holy pattern of life is a trait of God’s enemies, not His children (James 2:1). 

What makes Christianity different?

1. It is a spiritual belief that is open to all, regardless of age, religion, sex, or economic status.

“For God so loved the world that He gave His only begotten Son that whoever believes in Him shall not perish, but have eternal life.” (John 3:16)

2. It is a faith relationship with God that solves the problem of sin.  In other words, deliverance from sin is not achieved by one’s personal adherence to a system of works. One is delivered from sin by receiving God’s grace in Christ. A sinner is declared to be right with God as the merits of Christ’s life, death, resurrection and ascension are applied to him through faith. 2 Corinthians 2:21says it this way: “He [God the Father] made Him who knew no sin (i.e. Jesus, God the Son) to be sin on our behalf, so that we might become the righteousness of God in Him.”

Other faiths believe that salvation is based on good deeds or keeping certain laws.  Christianity recognizes that “There is none righteous, not even one” (Romans 3:10). 

The Bible clearly says that “He saved us, not on the basis of deeds which we have done in righteousness, but according to His mercy.”  (Titus 3:5)

3. Unlike Buddha, Mohammad, and other religious leaders, Christianity accepts that its Messiah, Jesus Christ, is still alive today. 

“…Christ Jesus is He who died, yes, rather who was raised, who is at the right hand of God, who also intercedes for us.” (Romans 8:34)

Jesus died on the cross for sinners, but was resurrected after three days.  His resurrection vindicated the truthfulness of His message. He was witnessed by many who were eventually martyred for their faith. The historic truth of Christ’s life and message has stood the test of time and will ultimately triumph over all other beliefs (Revelation 21:1).

Isn’t Christianity Just a Political Movement?

No. Real Christianity is not a political movement that seeks to change the world from the outside in. Rather, it is truth that radically changes one’s entire worldview from the inside out. Twentieth century British author, C.S. Lewis, said it well: “I believe in Christianity as I believe that the sun has risen: not only because I see it, but because by it I see everything else.”

There are many hypocrites and counterfeits in the world. And Christians can and do sin. But the general direction of a real Christian’s life is to increasingly love the things that are dear to God’s heart such as (see Acts 2:42) faithfully handling, believing and obeying His Word, being relationally committed to the people of His Church, worshipping Christ sincerely from the heart, and being winsome in the way one lives and shares His message of hope to the lost.

What’s Missing from the Average Person’s Picture of Christianity?

One Christian author* has answered the question like this: 

It’s like we’re in a war—in a concentration camp—and suddenly you’re hearing on the smuggled-in radio that the troops of deliverance have landed in helicopters five miles away. They’re conquering everything in their path and they’re just about to get to the gate and open the doors. And having lived all your life in this concentration camp, you’re now going to be set free.

That’s Christianity. It is news that God sent rescue troops into the world, namely Jesus Christ, and that at great cost to Himself He has conquered our enemy the Devil, opened the gates of the concentration camp, and welcomed us home.

And then you add the beautiful image of bride and bridegroom and realize that this is not just a soldier who simply frees you to go and do what you want to do. He’s your Husband, as it were, who has been separated from you for years and years, and you’re the wife who has been in the camp. And when the gates are opened, there He stands on the other side, and the affections are huge.

I remember watching at the end of the Vietnam war some of those magnificent videos of men who had been away from their wives—some of them I think up to five years. I remember watching them run toward each other and seeing them sweep their wives off their feet. My heart leapt and my tears flowed when I watched that kind of reunion. I believe it is this deeply emotional response to being rescued and united with God that is missing from so many people’s picture of Christianity.

Scripture taken from the NEW AMERICAN STANDARD BIBLE ®, Copyright © 1960, 1962, 1963, 1968, 1971, 1972, 1973, 1975, 1977, 1995 by The Lockman Foundation. Used by permission.

*Adapted from the article “Is Christianity Just a Bunch of Rules for How to Live?” is by John Piper. © Desiring God