Judaism (among other faiths) affirms theism - the belief in God. In practice, while religious people claim to affirm this belief as true, most have never seriously considered the question "What is God?" The problem is that merely stating that God is real says nothing about what God is; claiming to believe in something without precisely defining what that something is, is close to believing nothing at all. When pressed to describe specifically what they believe in, the average person only can repeat claims about God's actions, or about God's love for humanity. Even assuming that said actions actually happened, or that said relationship actually exists, this says little about the nature of God; it really only tells us about a particular historical incident, or about how people describe their relationship to the divine.
'Everybody's entitled to their own opinion' goes the platitude, meaning that everybody has the right to believe whatever they want. But is that really true? Are there no limits on what is permissible to believe? Or, as in the case of actions, are some beliefs immoral? Surprisingly, perhaps, many have argued that just as we have a moral duty not to perform certain sorts of actions, so we have a moral duty not to have certain sorts of beliefs. No one has expressed this point of view more forcefully than the distinguished mathematician W. K. Clifford: 'It is wrong always, everywhere, and for anyone to believe anything on insufficient evidence.' "
Others of similar stature have echoed this sentiment. Biologist Thomas Henry Huxley, for example, declared, 'It is wrong for a man to say that he is certain of the objective truth of any proposition unless he can produce evidence which logically justifies that certainty.' And Brand Blanshard has proclaimed that where great human goods and ills are involved, the distortion of belief from any sort of avoidable cause is immoral, and the more immoral the greater the stakes.
I am firmly persuaded by the logic. Thus, we should not believe in God without reason. It seems, then, that we would be obligated to search for reasonable arguments to believe in God. Finding such reason we would be obliged to believe in God; lacking such reason we would be obliged to dismiss God's existence as a unproven hypothesis.