Religious life is a life directed to personal perfection through agape according to the Bible and The Gospel as taught by the Lord Jesus Christ to his church (the body of Christ), or a life devoted to seeking union with God by humble obedience to the purposes of his holy will for oneself and all mankind.
In Orthodoxy and Catholicism, apostolic religious life is a form of consecrated life within the Church wherein the members profess vows of chastity, poverty and obedience within a Congregation or Community approved by the Church. Shared community life is an integral part of this form of consecrated life. They are called "Religious", who are called to "Religion". In other words, the Religious in the Church are those particularly vowed individual members of Religious Communities who practice the consecrated life of "Religion"; such a person is called "a Religious". This terminology is not intended to imply that the regular laity, single and married, who are baptized members of the Church are in any way irreligious or lacking in true devotion or genuine faith in Jesus Christ as the Son of God. The Apostle Paul himself taught that those who were unmarried or widowed and without a spouse were able to devote themselves to God without distraction, and that this is a preferable form of life, saying, "he who marries his betrothed does well; and he who refrains from marriage will do better". See First Corinthians chapter 7. There are unmarried single Religious who have formally taken vows, who are not bound to a community, and there are Religious who live in community and work in the outer world, and there are Religious who dedicate themselves to God in being bound to a Religious Community in seclusion.
In Protestantism a truly religious life is defined as distinct from the outward form of any kind of formal, institutionally organized religion, but not necessarily opposed to it, as being directed to God by means of the Five Solas, without any necessity of belonging to a convent or monastery. Protestant communities of like-minded believers have formed for mutual support and encouragement, such as the Amish, Hutterites and the Conservative Mennonites, and colonies of Puritans. Those communities governed by a chief pastor and senior leadership committees and boards of directors who regulated religious and social practice often resembled medieval monasteries and those communities that grew up around them in the centuries preceding the Protestant Reformation. Their descendants today believe as they did, that to belong to Christ as a member of His Body, is to be obligated in thanksgiving to God to live the devoutly religious life that He has revealed in the Bible, with all their heart, soul, mind and strength, and that it is impossible to do more than that; so that vows are not needed, except as a psychological help to remaining faithful by a contract of formal promise of commitment to do what the Christian is already bound to do as a true believer committed to God, a promise which is generally regarded as redundant, a rather silly addition to the life of a Christian, making a distinction which can unfortunately provoke a sense of elitism. See Romans chapters 12 and 13.
St. Basil of Caesarea and His Rule (novices.opwest.org) —Eastern Orthodoxy
1732 Sermon — Extraordinary and particular vows consider'd : as not necessary under the Mosaick, or expedient under the Christian Institution. A sermon preach'd before the University of Oxford, on Sunday in the afternoon, November the fifth, 1732. By Tipping Silvester, M.A. And Fellow of Pemb. College, Oxon (worldcat.org)