Hinduism is not a religion with laid down principles. A set of belief systems of Indian subcontinent was together called as Hinduism by the western powers that ruled India.
According to Hindu belief system God is one supreme formless power and we are all the manifestations this supreme power. The multitude of Gods in Hinduism are all manifestations of this supreme form. In fact all of universe is a manifestation of this supreme power. Science calls it different forms of energy. Hinduism says this energy is the supreme being, i.e god and he manifests in various forms.
The Raja Yoga (deep meditation) described in Bhagavadgita is the source by which one can attain the realisation of this formless all pervading nature of god which many sages have realised through the ages. The one who realises this becomes one with god.
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According to Hindu belief system, God is present every where and anywhere. God is inside you and throughout the cosmos. And the absolute form of god is formless nirakara Brahmand - the formless cosmos. Every thing and every one we perceive is a manifestation of the formless. Our body mass is a form of energy. So is the water we drink and the air we breath. All of nature is manifestation of this supreme power.
Hindu's have given abstract forms to elements of nature like Fire, water, Air and called them gods. They have laid out procedures in veda's to appease them and so many gods have come in to existence. This is way of understanding the importance of various elements in nature and to try to possibly control them.
For example Varuna Yagam is to appease the Rain god to get his blessing as Rains. The ritual is a process for burning different materials to generate smoke. Perhaps a scientific study of this can revel the actual scientific relevance behind such a process.
What we call science now has been woven in to the religious beliefs/story's in Hinduism so its not lost with time. A story is easier to transfer down to generations than abstract science.
The Hindu Yogis have already expounded many things in the vedic texts which are being proved through science like the Diameter of the earth, the planetary motion, etc.
Bhagavat-gita states that just like all rivers lead in to the sea, the worship of any god ultimately brings the devotee nearer to the absolute.
Hinduism also gives you a tool to find and experience god yourself - tapasya a higher form of Meditation. It is called Raja Yoga and has been clearly described in a scientific way by Yogi Patanjali in his work Yoga Sutras.