People have always worshiped a lot of different gods and paid their respects to them in ways that range from humorous to barbaric. While the Abrahamic religions teach that there is only one god, and this god is never changing, gods certainly have changed dramatically in human history. Gods have taken many forms and even the followers of monotheistic religions cannot agree on exactly what their god is like to this day. The ever-changing nature of god and religious practices raises serious questions as to where this god was throughout much of human history.
Some different beliefs
Early people usually had Animistic beliefs. They saw sprits and gods in everything around them. Gods were in the trees, water and even the animals they hunted. These were the gods of more generations of human beings than any other, and they are still followed today.
The Greeks and Roman gods are more typical of some of the gods people worshiped as society became more settled and complex. They had many gods and these gods often had very human qualities, squabbled amongst themselves or took the form of objects such as statues. As much as followers of monotheistic religions look down upon these kinds of beliefs, they were good enough for all of humanity for the long part of human history. Where was the unchanging monotheistic god when generation after generation of people lived their lives believing the nature of their god(s) took a form many would find blasphemous today?
Sacrificing for gods
Then there were gods that demanded all kinds of sacrifices, including human. While some of the most famous include the Aztecs (these gods needed human hearts for the sun to rise), the Inca (children crying before they were sacrificed was thought to bring rain) or the all-too-common practice of sacrificing children in the foundations of buildings, such gods were not at all uncommon in human history. From human sacrificial victims thrown into the bogs in northern Europe to Carthage practicing the large scale sacrifice of children in North Africa, it was found in far too many places.
There is no telling the horror these victims faced at their deaths (although some appear to have went willingly as part of their devotion to their gods). While it is easy to blame all this on human ignorance and superstition, should not this god that is supposed to be watching over everyone share a bit of the blame too? Why not correct the mistaken beliefs of his creations? How could he sit and watch such horrors take place for so many generations, in his name, and do nothing? While these beliefs are now considered blasphemous by the followers of monotheistic religions now and punishable by eternal torture, this god, if he sees and knows all, had no problem with people following such practices for many generations.
Why the confusion?
Then as now, there are just so many religions and competing beliefs. While people have come to agree that things like human sacrifice are wrong , they still cannot agree on what exactly this god wants to the point they often kill over it. From the time children were strangled for gods to those who die for religion to this day, why is it that a loving god, has not just taken a second to clear things up in a way that would leave no doubt? What kind of a being could sit and watch so many die for it, including the most innocent babies, and do nothing, especially when this being has infinite power to correct such evils with ease?
If a god wants people to worship it in a certain way, it seems like it could have easily started it with the first people. It could have clearly laid down the laws to follow then and called down from the heavens if the flawed minds of his creations ever went astray. Whatever anyone says about human nature, it is safe to say the vast majority of humanity would never go against what was the clear and definite word of a god.
However, until this day, nobody can offer the hard, conclusive evidence that there is only one god, let alone that god wants people to worship it in a certain way. Assuming this god is real, it has done a horrible job of communicating what it is really like and what it wants from people.