We had already seen the views of Western scholars who do not accept the authority of Quran and Sunnah. Their view is based from their observations. View of scholars for example from Andrew Lang coincidentally seems almost close to Islamic view.
In Islam, we view that the first human, Adam was revealed by the God, believes the God and worshiping the God the One. The nature divinely revealed is another synonymous of Islam. Says the God in Quran: "Indeed the law of life for the God is Islam."
The verse implies that the only teaching, wisdom, and law of life divinely revealed by the God to the earth is Islam. This teaching of nature is implanted in Adam's self. Says the God in Quran: "And turn your face to the law which is straight. The nature (divinely revealed) by the God since the human was created according to this nature. This is the law which is precious (valuable for spiritual and physical civilization) but many people do not realize it" (Surah ar-Rum: verse 30).
From this verse, we as Muslims are aware that Islam is not from human's evolution of thought. It is the nature divinely inspired and revealed by the God to every single human-being. Human was not introduced to his or her God by experience or lessons but by his or her nature which already exists in his or her selves. When Adam a.s was created, he was not being taught to whom should he devote himself. He knows his God and devoting himself to the God. Islam is not the result of human cultural development.
Though many books wrote that Islam is marked with the birth of noble prophet Muhammad s.a.w or the beginning of revelation to him but we believe that we are following the older path which is the path of patriarch Abraham a.s and his son, the noble prophet, Ishmael a.s. The reason why Christian fellows especially in Europe and Western world do not understand why we respect and also believe prophet Jesus Christ although we do not worship him like the God is that we are not following anything new. Islam is not marked with the birth of prophet Muhammad s.a.w. It is in everyone's self, nature. We do not worship Muhammad s.a.w nor anyone though Muhammad s.a.w was revealed with the Words in his heart because we still can differentiate the God and a figure. So, I wonder European scholars in 19th C always call Muslims as Mohammedan and trying to use articulation to offend people. This shows that Europeans are not tolerant, ignorantly emotional, and had exported this witless culture to other part of the world. We are not like Christian fellows to be identified with such identification and I realize that Christianity has many sects apart of those mainstreams in the West. Islam is derived from His Name, not of earthly names of figures who transmit the teaching to others. So, at this point, we are not the same. We do not use word play when it comes to the God and Divinity, or the creed to a certain individual as a transmitter of the teaching. No need to burden our head with what the God never says in scriptures as we have no right 'to speculate. We are not in the position to do so, and we should realize who we are.'
In human historical development, some human deviating from their 'nature' in creed. There are few factors which lead to this deviation toward the Absoluteness of the God:
Their creativity in imagination wants something which is anomalous and magical. So, they begin to imagine few things about the God and their imagination had gone far beyond the limit. Their imagination is also accompanied by life experience that they had faced. Imagination and whatever had been seen by their physical eyes were implanted into their mind. It influence the way on how they think and shaping their fantasy. They could not think anything about the God except with whatever that they had seen, the appearance of the God was made resembling whatever they saw and think it suits to Him. They faced difficulties to think about the Essence which is totally incomparable to anything in the universe or anything which revolves around them.
When they are performing worship, it is also difficult to focus their mind and attention without any focal point, so they need idols as the image of the God. Idols being by heating, hammering and shaped according to whatever preference that they have in their mind.
Actually, this is something which is common among practical Buddhists, not a Buddhist who is just in name because I did learned it and tried to practice that. Just for common sharing with brothers or sisters for general knowledge. People, I mean Buddhists who performed meditation without any image or rupam have higher chance to achieve enlightment. This is related to rupa and arupa jhaana. Basically these enables a person who performs thapa (meditation) to enter the facts of existence. There are some teachings on how to attain jhaana in a part called as Anapasati Suttam. It is how to sharpen ones mind and making him aware of everything that happens around or any changes that happened could immediately be sensed.
Introduction to angels and other kind of creatures invisible to human physical eyes turned to be personified or anthropomorphized into human appearance or characters. According to some people experience in life, everything which is alive and exist must have genders either male or female. It is difficult to think about creature who has no gender. Angels who has no gender being given genders and positioned as lower gods which are know as deities or gods. They could determine human life and fate. In many events in this life, this spirit or angel sometimes being equalized to the God until His Unity becomes ambiguous. This is what leads to animism and polytheism.
Extraordinary acts or any events happened which does not according to normal condition it should happen such as miracles or sacred comes out from a figure, for some human with middling mind who could not accept them as universal acts assumed as divinity acts. So, there is another assumption made up by them that the Essence of the God incarnating in the body of the person who performs miracle. Now these persons become God or at least equal to the God. Also the development of Buddha's image as focal point for prayers although Buddha never taught about any divinity regarding himself.
Last time, I didn't believe that Buddha is God though I bowed down and prostrated to images during pujas or worship. I usually did it secretly and silently whispering chants in my room where I kept Buddha's pictures in my wallet and files between my failed exam papers. I had no idols with me as my family members are all Muslims except me (by heart). I didn't pray according to Islamic way and only prostrated twice or three times according to time in a day, in morning, afternoon, and evening according to manuals that I get from temples for practices. I hate brother in law when he came by before he married my eldest sister because he interrupted my pujas as he stayed in my room. Buddha is only a spiritual teacher and those who attain enlightment are also known as Buddhas. Before him there were also Buddhas. It is not an exclusive term.
Sometimes, the God is being figured out like a human until every characteristics of the God becomes gods. This happens as in the example of Hinduism. There is also an explanation which says that obstacles for a religious teaching to be deviated is just too small or nothing at all. First is that, in ancient time, most teachings propagated by a transmitter has no obvious concept regarding theology and creed related to divinity. Most of teachings are taught and transmitted through oral since not many people could write as writing systems are not well developed so teachings could not be accurately preserved. Oral transmitting of a certain teachings could be over transmitted. Those who received the teachings from the first transmitter would put their own subjective into the teachings and propagate it to others. Not for long, maybe one or two centuries after the teaching was propagated, it becomes another new teaching with modifications here and there. Later, teachings written down are mixtures of those during the period of transmission and modifications.
There is also times where the writing of the teachings need some modification or adapted according to situation at the time for the religion to be spread out of the surrounding. It is to avoid the teaching from being obstructed by rulers and the people who followed the teaching from being tortured by governments' authority.
There are at certain place where the writers of teachings wanted to get benefits for themselves, for their tribes, or for their race through the teachings. They tend to magnify everything regarding the teaching that made them to over-write the teaching. This is not something weird, for example there is a news about a python had swallowed a goat. When the news reached another city, it become the python had swallowed a cow.