It is very difficult to clearly articulate all the similarities and differences, which exist between the beliefs about Dao, Allah and Brahman. On the one hand, it may be, in a very rough sense, generalized, that all and every one of them are deific, they all are of deific nature, they all rule the world and determine the lives of people, provide them with power to live and the wisdom to understand which way is right. It is important to understand a clear distinction which exists between Allah and the remaining two: Allah is a personalized deific creature. He is a god, who is, at the same time, a person. Allah is, in some respects, similar to people. One can refer to him as a personality. Moreover, he possesses some of the features, which are characteristic of a personality, of a human being. As an example, it is traditional to believe him to be male.
Allah is very special, as opposed to the other two, as he needs to be remembered and spoken of. It is necessary for the believers to speak of him and do things in his honor, to promote the teaching of Allah. The picture is quite different with Dao and Brahman. Taoists believe that speaking of Dao only takes one further away from actual Dao. Dao, expressed in words is not Dao any longer. Dao escapes verbalization, and, certainly, it is impossible to speak of Dao as a personality, as something, that or who would in any respect resemble a human being or any other creature for that matter. Dao is beyond it. Dao cannot have gender and needs to be understood, but not spoken of. Dao is a principle, the order of things, the pattern of the universe. In many ways Brahman is similar to Dao.
Brahman is also a substance, a material, out of which everything consists, and it is the collective sobriety, collective consciousness, in which one’s soul will dissolve, without, however, losing its personality. Brahman is everything, it is the principle and the action and the one, who acts: “The process of offering is Brahman; that which is offered is Brahman. Brahman offers the sacrifice in the fire of Brahman. Brahman is attained by those who see Brahman in every action” (The Bhagavad-Gita, ND).
Brahman represents the entire diversity of creation in itself, it both represents and out of it such diversity derives. Everything and everybody derives from Brahman and Brahman is the goal, the peace, the happiness, the main ambition of every spiritual being: “When they see the variety of creation rooted in that unity and growing out of it, they attain fulfillment in Brahman” (The Bhagavad-Gita, ND).
This is why it may be inferred, that Brahman is much closer to Dao than to Allah. However, this is only a very relative comparison, since all the three of the concepts are very difficult to explain and express. For many people it takes lives to even try to understand one of them, so diverse and multiple are the dimensions, which need to be addressed for the sake of proper understanding. And it is, probably, right to assume, that the one, who will achieve the understanding will achieve Brahman, will approach Dao and will be amazed by Allah. Trying to understand any of these concepts requires significant will for self development, and this is, probably, yet another similar feature, something that brings these three different and complicated concepts together and unites them. Lastly, another thing, which formally serves as a common feature, is the region, in which all three of the concepts originate from, such being Asia.