Religion is a guide book of a path to perfection of an individual.
There is a huge mountain called life. The tip (or top) of the mountain is perfection. Every living creature including human being starts its life at bottom of the mountain and spends its life to reach to the top of the mountain (perfection).
Every person cannot reach the perfection in a life. Only few people have reached the perfection much before their death. The extracts of successful and failure cases of lives of people are available as guide books. Guide books help people in avoiding major blunders while climbing the mountain. One cannot follow other's path exactly while climbing a mountain because each person’s body structure, step size, speed and stamina are different. Similarly one cannot follow exactly other's path to perfection because mind, body, concentration levels, behaviour, feelings, life style and environment are all different. There are infinite unique paths to climb a mountain. Some paths may intersect or overlap. Similarly there are infinite unique paths to perfection. The path to perfection followed by a living creature is always unique.
Whether you read one guide book or multiple guide books or don't read any guide book, your path to perfection is always unique. A guide book of a unique path is also unique. Therefore your religion is always unique. That means, your religion can never match with religion of any other person.
Every living creature is trying to improve its life because it feels that current situation of its life is not perfect. The creatures other than humans also follow their own unique paths to perfection. As humans can share knowledge, we read lives of successful people and try to copy them. In this process, we forget that each person is unique and we cannot do exactly what the other person has done. That's why we feel like many people are following one religion though in reality each person is following his/her own unique religion. Religion is not related to a group or community. Religion is strictly related to an individual.
Following other's religion is like wearing other's dress. We cannot walk and act like other person just by wearing his/her dress. Similarly we cannot gain benefits by following other's religion. We need to read/understand other's religion as a guide book or guidelines and shape our own life. Following other's footsteps blindly is always wrong. If we try to act like other person for whole life, we can never get satisfaction. It is like wasting a life if we don't customize or create a religion for our own life.
When you do something, if it is improving your work, improving your life, improving your satisfaction levels then you are following a proper path in life. There are more than 7 billion unique religions in our world that are followed by human-beings. Other living creatures also follow their own religions to reach the perfection. Religion is not related to God. Religion is about you, your betterment, your improvement and your level of perfection. Every living creature is trying to live better. The thought process of living better is a religion. It is up to you to call it a religion or something else.
Summary of religion: "You keep doing whatever improves your life".
The people who tried a path to perfection and achieved some level of perfection are teaching the steps followed by them as religion. It does not mean that the steps that helped him/her will also help you. If those steps are helping you to improve your life, you can follow them. Otherwise you simply ignore them and create your own steps. When a person shows a new path, it does not mean that the other path shown by other person is wrong. This person tried one path and found it was good. The other person tried another path and found that was good. It is up to you to decide whether to follow this path or that path or completely a new path. Whichever path you take, you cannot exactly follow other person's path. Finally your path will be a unique path though it may resemble one of the earlier paths.