Faith, Belief, Religion, Spritualism, Adhyatm, Dharma & Hinduism : At a Glance

Let us study and analyse these concepts one by one

A. Belief :-
Definition:
Oxford :
"An acceptance that something exists or is true, especially one without proof."
"Trusting something without proof."

B. Faith:-
Definition:
Oxford: "A strongly held belief."

C. Religion :-
Definition:

"An institution that mostly sets itself as definer, custodian & ultimate authority of the faith."

Oxford :-"A particular system of faith and worship."

Wikipedia :-
"From L. religionem (nom. religio) "respect for what is sacred, reverence for the gods, sense of right, moral obligation, sanctity", "(obligation, the bond between man and the gods") is derived from the Latin religiō(Meaning: to bind), the ultimate origins of which are obscure."

D. Spiritualism :

Wikipedia :
"Spiritualism is a religious movement based on the belief that the spirits of the dead exist and have both the ability and the inclination to communicate with the living. "

E. Adhyatm:-
Adhyayan +Aatm ie study of self,

Adhyatm is Belief and practice of following :

• The truth of universe is within self,
• Objective is realization of universe through self Realization.

F. Dharma :

Wikipedia :
"Key concept with multiple meanings in Indian Religions like Hinduism, Buddhism, Jainism, Sikhism and others. There is no single-word translation for dharma in Western languages.

In Hinduism, dharma signifies behaviors that are considered to be in accord with Ṛta, the order that makes life and universe possible, and includes duties, rights, laws, conduct, virtues and "right way of living".
 In Buddhism, dharma means "cosmic law and order", and is also applied to the teachings of Buddha. In Buddhist philosophy, dhamma/dharma is also the term for "phenomena".
Dharma in Jainism refers to the teachings of tirthankara (Jina) and the body of doctrine pertaining to the purification and moral transformation of human beings. For Sikhs, the word dharm means the path of righteousness and proper religious practice."

G. Hinduism :
Wikipedia:
"Hinduism is an Indian religion and dharma, or way of life,widely practised in the Indian subcontinent and parts of Southeast Asia. Hinduism has been called the oldest religion in the world, and some practitioners and scholars refer to it as Sanātana Dharma, "the eternal tradition", or the "eternal way", beyond human history. Scholars regard Hinduism as a fusion or synthesis of various Indian cultures and traditions, with diverse roots and no founder."

Belief of Hinduism :
Hinduism does not have a "unified system of belief encoded in a declaration of faith or a creed", but is rather an umbrella term comprising the plurality of religious phenomena of India.

The word Hindu :
Wikipedia :
 "Starting with the Persian and Greek references to the land of the Indus in the 1st millennium BCE through the texts of the medieval era, the term Hindu implied a geographic, ethnic or cultural identifier for people living in the Indian subcontinent around or beyond the Sindhu (Indus) river. By the 16th century, the term began to refer to residents of the subcontinent who were not Turkic or Muslims."

Conclusion : Hindu is an alien word for India, used by Persians as a geographical notifier.

So called "Hinduism" is a foreign word used by western people as a superset of people (Other than Abrahamic Religions) of South Asia and their Beliefs, cultures, traditions and ways of life.

Is Hinduism a Religion?

According to the Supreme Court of India,

"Unlike other religions in the World, the Hindu religion does not claim any one Prophet, it does not worship any one God, it does not believe in any one philosophic concept, it does not follow any one act of religious rites or performances; in fact, it does not satisfy the traditional features of a religion or creed. It is a way of life and nothing more".

Hinduism includes a diversity of ideas on spirituality and traditions, but has no ecclesiastical order, no unquestionable religious authorities, no governing body, no prophet(s) nor any binding holy book; Hindus can choose to be polytheistic, pantheistic, panentheistic, pandeistic, henotheistic, monotheistic, monistic, agnostic, atheistic or humanist. Ideas about all the major issues of faith and lifestyle including: vegetarianism, nonviolence, belief in rebirth, even caste, are subjects of debate, not dogma.

Because of the wide range of traditions and ideas covered by the term Hinduism, arriving at a comprehensive definition is difficult. The religion "defies our desire to define and categorize it". Hinduism has been variously defined as a religion, a religious tradition, a set of religious beliefs, and "a way of life".From a Western lexical standpoint, Hinduism like other faiths is appropriately referred to as a religion. In India the term dharma is preferred, which is broader than the Western term religion.

Supreme Court , further :

"Hinduism does not have a "unified system of belief encoded in a declaration of faith or a creed, but is rather an umbrella term comprising the plurality of religious phenomena of India."

Hindu Dharma comprises of 4 major Dharmic Schools ( 'Hindu', Buddhist, Jain, Sikh) which include a diverse paradigm of philosophies:
"Hindu", Buddhist, Jain, Sikh

The Explanation II of Article 25 reads:

"...The reference Hindus shall be construed as including a reference to persons professing Sikh, Jaina or Buddhist religion and the reference to Hindu religious institutions shall be construed accordingly," 

Common Beliefs of Dharmic Schools:
Reincarnation,
Karma,
Moksha,
Advait
&
Above all "Omkar"

Omkar : Om is the most important spiritual sound. It refers to Atman (soul, self within) and Brahman (ultimate reality, entirety of the universe, truth, divine, supreme spirit, cosmic principles, knowledge), Akalpurush, Advait (Non Duality).

Advaita: The term Advaita refers to its idea that the true self, Atman, is the same as the highest metaphysical Reality (Brahman).
In other words : All living beings /things are forms of same indivisible Brahman.

Plurality: The belief that there can be multiple ways of religion/spirituality/faith and all may co-exist together.
Opposite: Binarism, the belief that there is only one true religion , an essential belief of Abrahamic religions .

Conclusion:

As evident from above, Hinduism is neither a faith or religion, but plural way of life of Indian cultures whose spiritual belief generally based on Reincarnation, Karma, Advait , Moksha through self realization, and there being no fixed way, sadhak is encouraged to find and follow his own preferred way of self realization.