Kevin DeYoung writes (original source – https://www.thegospelcoalition.org/blogs/kevin-deyoung/theological-primer-religion/):
The etymology of the word “religion” is unclear. Over the years, many have agreed with Cicero (106-43 BC) who derived religio from relegere, a Latin word meaning to gather together or to reread. On this account, religion is the diligent study of the things pertaining to God. Others have preferred the explanation given by the church father Lactantius (c. 250-325), which Augustine (354-430) adopted, that religio comes from religare meaning to fasten or to bind. With this etymology, religion is the binding or reattachment of man to God.
In contemporary parlance, “religion” is often construed in entirely derogatory terms. Even by Christians, religion is supposed to be the opposite of a relationship with God. Or religion is about trying to earn God’s favor. Or religion is about a stultifying system of rituals, dogmas, and structures. The problem with this disparaging understanding of “religion” is threefold.
(1) This is a relatively new way for Christians to speak. John Calvin wrote the Institutes of the Christian Religion. Jonathan Edwards wrote on Religious Affections. Pastors and theologians, especially in the age of awakenings, often wrote about “religion” or “true religion” or “real religion.” Our forefathers were well-aware of religious hypocrisy and false religious systems, but they did not equate “religion” with works-righteousness.
(2) The word “religion” occurs five times in the ESV and is, by itself, a neutral word, translating either deisidaimonia (reverence for the gods) or threskeia (religious worship). Religion can refer to Judaism (Act 26:5) or the Jewish-Christian faith (Acts 25:19). Religion can be bad when it is self-made (Col. 2:23) or fails to tame the tongue (James 1:26). But religion can also be good when it cares for widows and orphans and practices moral purity (James 1:27). There is no biblical ground for making the practice of religion a uniformly negative phenomenon.
(3) In castigating “religion,” we may be unloading more baggage than we realize. People tend to equate commands, doctrines, structures, and rituals with religion. That’s why people want to be “spiritual but not religious.” And yet, Christianity is a religion that believes in commands, doctrines, structures, and rituals. As a Jew, so did Jesus. Jesus did not hate religion. On the contrary, Jesus went to services at the synagogue and operated within the Jewish system of ritual purity (Mark 1:21, 40-45). He founded the church (Matt. 16:18) and established church discipline (Matt. 18:15-20). He instituted a ritual meal and called for its perpetual observance (Matt. 26:26-28). He told his disciples to baptize people and teach them to obey everything he commanded (Matt. 28:19-20). He insisted that people believe in him and believe certain things about him (John 3:16-18; 8:24).
In short, we give people the wrong impression about Jesus and affirm unbiblical instincts about true spirituality when we quickly dismiss “religion” as antithetical to the gospel and at odds with God-honoring piety.