Even if God exists, why is it necessary to believe in Him? After all, we do not have to ‘believe in’ everything that exists. There may be a stone lying under a tree in the jungles of Africa, but we do not have to believe in it. Do we? What exactly is the meaning of ‘belief in God’?
I tend to agree with you that we do not have to believe in everything that exists or has a potential for existence. However, it would become easier to appreciate the answer to why is it necessary to believe in God, if we first understand the true meaning and implication of ‘belief in God’.
The phrase, ‘belief in God’ implies the recognition of and the reciprocation in the relationship that one has with his creator, provider and sustainer. In other words, it is not mere existence of something, which makes it necessary for us to believe in it. On the contrary, it is actually our relationship with that ‘something’, which exists, which makes it binding upon us to believe in it. This ‘belief’ entails two steps: First, the recognition of the relationship, if any, which exists between the ‘something’ that exists and ourselves. Next, the determination of the responsibilities that become binding upon ourselves in the relationship with the ‘something’ that exists.
Keeping the foregoing explanation in perspective it should be clear why is it not necessary to ‘believe in’ a stone that may be lying under a tree in the jungles of Africa. Merely because we don’t have any thing to do with that stone – a complete lack of relationship between the stone and ourselves and a lack of any requirement of reciprocation on our part – we do not ‘have to’ believe in the existence of the stone, even if it does, in fact, exist. However, if I were informed by an authentic source, that one of my great grandfathers had hidden a treasure under a particular stone, under a particular tree, in a particular jungle of Africa; this information would suddenly develop a relationship between me and the stone lying under one of the trees in the jungles of Africa. Now, if I believe the information to be correct, I am likely to plan a number of actions, as a response to the relationship that has suddenly developed between me and the stone. All these actions would actually emanate from my ‘belief in’ the existence and the placement of the stone and the information that I have received about its ‘relationship’ with me.
‘Belief in God’ emanates not only from the fact that He exists, but from my realization of the relationship that I have with Him and from my inherent desire to respond to Him in the most appropriate manner. Thus, ‘belief in God’ is not like ‘belief’ in something, which does not relate to us. On the contrary, it is more like the realization of the fact that the person I live with is my father. This realization, in turn, develops a relationship between me and that person, the appreciation of which requires me to behave with that person in a particular – morally suitable – manner. Obviously, my behavior with that person is based on my ‘belief’ that he, in fact, is my father; It is my moral obligation to respond to him in a respectful and polite manner. If, due to some reason, my ‘belief’ regarding my relationship with that person is altered, it would have an obvious effect on my relationship with that person and, suddenly, there would be a change in the nature of my interaction with him.
God does not merely exist. On the contrary, He is the being, Who has brought me to life; Who provides to sustain my life; Who has bestowed me with all the invaluable blessings that I enjoy in life; Who ultimately controls all the factors, which effect my life; and Who would, one day, end my life. This realization about God – and not merely His existence – is what develops a relationship between me and Him. It is the recognition of this relationship and the desire for the appropriate reciprocation in this relationship, which Islam – as well as other divine religions – term as ‘Imaan billah’ – ‘Belief in God’. Thus, ‘belief in God’ is one of the moral obligations, the fulfillment of which becomes incumbent upon man, as soon as he realizes that God is his creator, sustainer, provider and controller.
Thus, if God is truly our creator, sustainer, provider and controller, then ‘believing in Him’ is an obvious requirement of accepting and submitting to one of the most significant truths about this world, about ourselves and about life.
I hope this helps.