God is a belief that someone or something is having power to create, power to cure, power to control, power to change and power to destroy. You keep the belief in something and it becomes god for you. It can be you, other human being, other creature, material or energy.
You can install the god wherever you want. It can be in one place, in multiple places, in multiple people or in multiple creatures. The power of god exactly equals to your belief of what powers He has. The power of each god you install is different because you believe each god is different. And also the power of god differs with respect to each person who installs the god. For example, if two people install the god in one person but their belief of power of god is different. Then the god will demonstrate different power with each one. If the first one believes god has power to cure and the second does not believe in power to cure. Then the god can demonstrate the power to cure only with the first person.
By looking at a god curing someone, if you just want to try your luck, you may not get any change. You need full belief that he can cure your disease. Only then you can feel some change. If you really have 100% belief that someone's touch can cure your disease, it cures.
Here god man is not important. Belief of the person, who believes that he is god, is important. People worship people, animals, statues, stones, pictures and so on. Which one you treat as god is not important. Only how much you believe in that god is important.
If you install your belief in yourself, you become your god. You will have all the powers that you believe. If you believe that you have power to cure, you can cure your diseases. But you cannot cure diseases of other people till they install belief in you.
Hypnotism also works with similar concept. If you believe that the other person can hypnotise you, you can get hypnotised. If you strongly believe that the other person cannot hypnotise you, you will never get hypnotised.
Few gods have shown magic, super natural powers, healing power, material control, mind control, mind reading, lived long, lived without food, shown knowledge and so on. All these are true. Any human being can gain all these powers with high levels of concentration.
Read article on Mind to know what all we can do with mind power.
Note: Though it is possible to gain all the powers, most of the people who are claiming that they have full powers of mind control or material control may be wrong because one can change everything that is happening now if one has mind control and material control.
The people who gained mind control and material control can demonstrate all types of powers. As only your mind can make changes in your body, the people with power of mind-control make you (or your mind) believe that he can make changes in your body. Then your belief allows him to make all changes whether they are healing or damaging.
Belief of the person allows him/her to withstand extreme strain. In this period, body cells get transformed to withstand the strain. If the strain continues for very long time, cells of whole body get transformed. Later that person can live in the strain normally. Saints (yogis) get used to withstand extreme hunger for days and months. When they start very long meditation, they slow down or shutdown most of the body functions thereby reducing energy consumption to a bare minimum. As body cells stay in this condition for a very long time, they get transformed to withstand the strain. After saint comes out of meditation, he/she can live without food or with a minimal food.
If we have positive beliefs, we get positive results. If we have negative beliefs, we get negative results.
When child comes home for holidays from studies, mother becomes very happy. The sick mother becomes alright. Here the child has not done anything. The mother strongly believes that she will be happy in child's presence. That happiness improves her health. Now we can call the child a god but we call it mother's love because there is a relation. If a stranger's health improves when the child meets the stranger, then the child will be treated as god though the child has done nothing with the stranger.
It happens with everyone in relation or out of relation. When we meet most loved person, our mental strains come down and physical health improves. We call it love, not god. Same thing happens when we go to temple, church or mosque. We call it god, not love. In both the situations, it is your belief that improves your life. If a holy place really has power, it should give same feeling and improvement for all people that enter it irrespective of their belief.
Similar things happen for negative beliefs also. When you come out of your house, see something and believe it is a bad sign to start your day, then you are anticipating something bad to happen that day. If really something bad happens, your mind accepts/compromises quickly as you are expecting it. With this the bad becomes worst. If you start your day by assuming something good will happen on that day and something bad happens, then your mind tries to change the situation by fighting little longer to make it good. With this the bad remains bad or improves little and becomes good. When some incident happens in your life, it is your belief that decides whether to make it good experience or bad experience.
In rituals, some people believe very strongly that god comes in somebody's body. They will be eagerly waiting for that moment. If it does not happen for a long time, their eagerness crosses the tolerance and their mind takes the role of god and control over the body. Usually it stays till people agree for what it says. The person with god in the body does what he/she believes god will do if god is present here. There is a chance of showing super natural powers in this situation. Usually this incident happens when something wrong is done with the god. So the belief is that god comes in someone's body and tells them to change the wrong thing. Whoever believes it strongly gets vibrations in the body and behaves like a god.
Same thing happens if a person believes that a ghost or demon has taken over his/her body. Usually it happens after the person goes in wrong place like burial ground. Sometimes the person demonstrates scary powers. Because of the powers they demonstrate, people think that the real god or demon has come into the person's body. If young children see and believe or get scared of this, their body reacts easily with similar triggers in future. The vibrations we get in our body when we hear deep devotional song or very scary incident are also because of our belief in these incidents.
With power of mind, we can force the god (god's mind) to appear in front us. If god's mind does not have body, it may come in someone's body and talk. But most of the cases, it is an illusion created by our mind. When we believe, god should appear with this level of devotion, our mind creates the illusion to satisfy our belief.
Few examples of god appearance are:
When a person meditates to gain a particular power, mind creates an illusion of him/her gaining the power after the person gains enough concentration. Usually people meditate on a particular god to gain super power. When the person gains enough concentration, mind creates the illusion of god's appearance and interaction. The person can use the power after he/she believes that god has given the power. The power can be a weapon and/or a protection from weapons and people.
When saints meditate to gain concentration, they gain control in a progressive order of mind power. The order is thought process, senses, feelings, emotions, body functions, mind reading, mind control and so on. Read mind article for more. After they get control over senses, feelings and emotions, they see everything is of equal importance in the universe. So after they achieve high levels of concentration and gain super natural powers, they use the powers only for their purpose of life.
But the people who meditate to gain a particular power or a set of powers don't go through the order of mind power. They concentrate only on the required power and get it. As they don't have control over their feelings and emotions, they misuse the power and harm other people and creatures. We call them demons.
To protect innocent living creatures from demons, saints who have higher levels of concentration read mind of the demon and understand his/her belief of powers. By finding loopholes in the demon's belief, the saints develop a person who can reciprocate demon's powers. We call this person a god. After god is developed and ready, saints send this message to all saints and demons through mind communication. Saints explain very clearly the minor details that are missed while demon has wished for super powers and how these mistakes are taken as advantage to kill the demon. Saints protect god till demon understands that he/she will be killed soon. After multiple attacks on god fail, demon's belief of death increases. God will attack the demon when demon's belief of death is at the highest and demon dies.
Every time one or more demons rise with super powers, saints create a god and give their powers. That is how we have so many gods in ancient history of India.
Read Definition of spirituality to know your own god.