The word religion actually means "to bind back". It speaks of the reality that man has been searching for the way to bind himself back to God - that's why there are thousands of religions. Christianity is the opposite of religion because it is not what man must do to bind himself back to God but what God has done to bind man back to Him. Religions teach man MUST do specific things in order to acquire the endgame - be it heaven, nirvana, happy-hunting-grounds. One religion teaches one thing and another teaches something different, but they ALL teach the onus is on the man to make himself worthy of God.
Jesus is God in the flesh and He died on the cross to pay for the sins of the world. God's requirement is FAITH. We don't earn, merit, work for or deserve heaven, we are given heaven as a gift by the grace of God and we receive this gift by faith. Christianity is the polar opposite of religion.
Excellent response. I was about to post something similar until I read yours.
If you look at the various definitions of religion, and its etymology, it takes on a very negative connotation which can be essentially boiled down to bondage. God’s Truth is supposed to make you free (John 8:32). Religion enslaves you in ceremonies, dogma, tradition, rituals, superstition, etc., all the things Paul argues against in Galatians and Colossians (rudiments & elements of the world). Or as we see in Hosea 6:6, quoted by Jesus to the religious of his time - For I desired mercy, and not sacrifice; and the knowledge of God more than burnt offerings.
Believers are not servants, or even friends of God. We are His Children, if led by His Spirit (Romans 8:14). That means relationship, not religion.