The concept is strange. The concept is interesting. Above all, the concept is oddly beautiful.
When we think of nature, it is abundant, anomalous, adaptable, alien, alluring, anarchic, arbitrary... Amazing. All of these adjectives could also be used to describe God - abundant in forgiveness, anomalous in his approach to evil, adaptable to the needs of his people, alien in our lack of understanding him, alluring in human desire to understand him, anarchic in characterization, and arbitrary in his warnings.
Baruch Spinoza, an influential philosopher of the 17th Century, viewed god and nature as two names for the same reality, namely a single fundamental substance which is the basis of the universe, and all lesser beings such as ourselves are simply modes and modifications. Everything that exists in nature is one reality, and there is only one set of rules governing the whole of the reality which surrounds us and of which we are a part. Through this theory, Spinoza was considered the greatest advocate of Pantheism, the belief that everything composes an all-encompassing and impersonal god.
It is said that there are more pantheists than theists in the world. For example, Hindu literature and religious text contains pantheistic ideas. The Atman (the human soul) is indistinct from Brahman (the unknown reality of everything). Examples of pantheistic ideas can also be found everywhere from Christianity, Judaism and Buddhism to Taoism, traditional African and American religions and Ancient Greek mythology.
The phrase "God is nature" links together themes from different religions. Firstly, it takes the personification of earth, Gaia, from Greek Mythology. She was a primordial deity, the creator of the Earth and all the universe, the very embodiment of nature. You could add the idea of the Jewish God Elohjim as an omnipotent creator of nature or the animalistic visions of Native American traditions.
Nature is powerful, majestic, ordered even in chaos. It has a complex system where everything works together in harmony to create beauty. What is God? The Creator and Sustainer of life. What is Nature? The Creator and Sustainer of life. If you leave the idea of a conscious Christian or Islam God, and think purely about an impersonal and formless God, this concept is very attractive.
If you look out of the window, take a stroll through the park, appreciate your surroundings, you learn to respect the beauty and energy of nature. Because nature isn't dead. It isn't dormant. It's bursting with energy, actively working, changing , improving with every moment. The power of nature is breathtaking when you really take it in, and I feel that understanding the strength of the universe is akin to meeting God, if you ever were to.
Christians, Jews, and Sikhs alike believe that God is part of the world, all around us in everyday life. Whether you believe it or not, it is a comforting idea for many to feel that God is all around us, in the air we breathe, the fruit we eat, the colors we see and the scent of rain on arid ground we smell.
I leave you with one final quote to reflect on from Helen Keller:
"The best and most beautiful things in the world cannot be seen or touched - they must be felt with the heart."