What does it mean when said, "Christianity is relationship and not a religion?"
It is both — and the saying is reaching for something true but stated wrongly. Scripture never sets religion against relationship; it sets false religion against pure religion. Christianity is a religion — the one where God does the reaching, coming down as far as a cross.
You have probably heard a Christian say it: Christianity is not a religion, it is a relationship. It gets said from pulpits and printed on church walls, and the people who say it mean well. But taken at face value it is not true, and the Bible will not put it that way. Scripture never sets religion against relationship. It sets false religion against true religion.
James is blunt about it.
James 1:26–27 (NKJV)
If anyone among you thinks he is religious, and does not bridle his tongue but deceives his own heart, this one's religion is useless. Pure and undefiled religion before God and the Father is this: to visit orphans and widows in their trouble, and to keep oneself unspotted from the world.
Look at what James contrasts. Not religion against something better, but useless religion against pure religion — a man performing outwardly while his heart stays untouched, set against a man who knows God and therefore cares about the people God cares about. The word itself is not the problem. Christianity is a religion. The question worth asking is what kind.
So what is the saying reaching for? Something real, and it deserves to be put properly. It is a claim about direction. Religion, as most people use the word, is man reaching up to God — rituals to perform, rules to keep, offerings to bring, all in the hope of becoming acceptable to Him. On that definition every religion in the world moves the same way: upward, from man to God. The Christian faith announces the opposite movement. God has come down to us.
That is why the Bible never treats our love for God as the starting point.
1 John 4:19 (NKJV)
We love Him because He first loved us.
The order in John's sentence cannot be reversed. God's love comes first, and our love is the response it creates. We did not go looking for Him; He came looking for us. Religion begins at our end. The gospel begins at His.
And He did not come down a little way. On the night before He was crucified, Jesus told His disciples:
John 15:13 (NKJV)
Greater love has no one than this, than to lay down one's life for his friends.
He was not offering a general observation about noble sacrifice. He was describing what He would do the next morning. The God men try to reach by ritual and effort came down Himself, took on flesh, and laid down His life for His friends. The work we could never do has been done.
That cuts closer to home than most people expect. If knowing God is the point, then a person can hold Christianity as a system — the label and the church habits — and never know Christ Himself. Jesus defines eternal life in exactly those terms:
John 17:3 (NKJV)
And this is eternal life, that they may know You, the only true God, and Jesus Christ whom You have sent.
In Jesus' own words, eternal life is not a reward for religious performance. It is knowing God, and knowing the Son He sent. We do not get to heaven because we are tagged as Christians. We are saved through trusting in Jesus Christ, and to trust Him is to know Him.
Some hear the saying and conclude that the church, its teaching, and its commands are all “religion”, and that a person needs nothing but a private Jesus. But the religion James calls pure is not a man alone with his own thoughts. It is a life that knows God and shows it — among His people, and in care for those nobody else is caring for. The saying was aimed at earning. It was never a licence to walk away from what Christ commanded.
Why, though, does His love come first? Because it was never a reaction to us at all. Religion imagines a God whose favour must be won, whose love switches on once our performance is good enough. But the Scriptures state plainly that “God is love” (1 John 4:8). That says more than that He loves; love belongs to His very being. He is one God in three persons — the Father, the Son, and the Holy Spirit — and love has been given and received among them from all eternity. He did not make us because He lacked someone to love. His love was already full, and He made us freely out of its overflow. A love like that owes nothing to our performance. It cannot be earned, only received.
Christianity is a religion. It is the one religion where God does the reaching. Every other one asks you to make your way up to Him. This one tells you He has already come down — as far as a cross — to bring you to Himself. You do not have to reach up to God. He has come down to you.