You have to examine your physical body and investigate to see whether there is anything permanent or unchanging within your body. As a result of this investigation, you will see that the body is a collection of ever-changing material states and that there is nothing permanent in them. There is instability in them as they are always arising and vanishing, and there is no self or ego-entity to be found therem. As well as realising the exact nature of the body in this way, you have to examine the mind. As you go on analysing and scrutinising the mind, you will find that what you call your mind is just a stream of rising and vanishing mental states in which there is no substance.
Every mental state is subject to change.
They are arising and vanishing more rapidly than the material states of the body, and there is no permanent self there either. When you come to this understanding of your body and mind, your ignorance as to their nature disappears and the wisdom of full realisation dawns to your own true nature. When you look at the external world from the same perspective, you will see that the whole world is the same nature as your own body and mind. When you achieve this understanding of life in the world, you will also see the opposite side - the unconditioned, unchanging, eternal state of perfect calm and serenity, free from all suffering. To achieve this goal requires no worship, no ritual, no belief in any dogma.