The Arab invaders called the Sindhu Hindu, hence people living on the other side of the river were termed as Hindus and their different faiths were collectively termed Hinduism. If Hinduism has thrived for thousands of years, it's because it evolved with time and flowed like a river accepting water from tributaries, not allowing the water to stagnate. Hinduism allows an individual to question its tenets and follow it only if the individual finds it convincing. An individual is free to follow the stream of his or her choice. In a family, the mother could be an idol worshipper, daughter a dualist, father a monotheist and son an atheist. A Hindu can visit the places of worship of other religions. A prayer can be offered in any format or language, even self composed.
Hinduism emphasises on duty - pita dharm, putra dharm, raj dhara... The guiding principles are 'ekam sat vipra bahauda vadanti (truth is one, saints refer it by different names), udara charita nam tu vasudhaiva kutumbakam (An open mind considers mankind one family) and aano bhadra krtavo yantu vishwatah (Let noble thoughts come from all directions)'. The spirit of Hinduism was in Meerabai's revolt against a highly patriarchal society for her devotional love. It reflected in the act of emperor Humayun, who rushed to save a Hindu queen on receiving rakhi from her with a request for help against a Muslim aggressor, in the supreme sacrifice of Guru Tegh Bahadur to save Hindus from Aurangzeb's religious terrorism. Mother Teresa's is Hinduism personified.
Untouchability is a blot on Hinduism. But Hinduism has also produced hundreds of Dalit saints from Valmiki to Ravidas revered by all Hindus. According to the Bhagwatgita, God resides in everything in the universe, hence serving mankind and nature is the best prayer offered to the Almighty. Gandhi said "Accept only those things from traditions which you think are right and reject practices carried out in the name of religion which are against morality. Hinduism has love of Jesus, compassion of the Buddha, non-violence of Mahavir and brotherhood of Mohammad. Ideas of Sarvodya (uplifting all) and daridra-narayan (God resides in the poor) were inspired by the Gita.
Gandhi described Hinduism as the most tolerant creed because it is non-proselytising. "A Hindu refuses to change his religion, not because he considers the faith to be the best, but because he knows that he can complement it through the reforms. Hinduism is like the Ganga, pure and unsullied at its source, but taking in its course impurities on the way. Like the Ganga, Hinduism is beneficent in its total effect. It takes a provincial form in every province, but the inner substance is retained everywhere. Gandhi's assassination was an attempt to terrorise the masses who identified themselves with Bapu's thought, deed and action. It was an attack on the common man, who, though illiterate, kept alive love, tolerance and brotherhood enshrined in the works of Kabir, Sur and Tulsi.