There are many different ideologies in the world, from nihilism to humanism, Catholicism to Shintoism, and even the political logic of both Machiavelli and Burke. Each of these ideologies is different on fundamental levels. Some of these say that humans should treat their ancestors with reverence. One example of this is the Japanese religion of Shintoism. Others will claim that you should treat an omnipresent being with reverence (such as the Judaeo-Christian religions). Each ideology will treat humans and human nature differently. Some say that humans are cruel and terrible with few, if any, redeeming qualities. Some ideologies claim that humans are naturally good and that they have abilities that make them different from each other, thus giving humans inherent value. However, the different ideologies each have a single quality that is seemingly universal: that is that there is some nature of human beings and, thus, each ideology has a concept of morality.
Morality is the idea that humans have an innate set of principles that they should follow and that by not following them, you are an outlier to the society or group which you are a part of. Examples of this are in the different theologies mentioned above and in the laws that people create through both time and various governing bodies. Christian theology gives people both the Ten Commandments and the book of Leviticus, which are series of rules that one who is in the religion must follow in order to be moral according to its text. Another example of morality can be seen in the laws that govern people. All governing bodies have laws and many of those laws revolve around how people are to treat and act toward one another. Akin to religion, how an individual acts in accordance with the law will dictate how the society treats the individual. Someone who breaks the law will be penalized by the society that they are in by becoming a deviant to the majority and by the government through some sort of correctional behavior, be it through prison, fines, or even capital punishment if the individual did something that the society would find reprehensible.
There is a problem with the idea above in regards to morality and the views that people have on it. Many people feel that there are acts in this world that are "right" or "wrong" with little to no gray area. This mindset is why morality cannot be objective. Each individual has something that they value, whether it is something as simple as individual happiness or something as complicated as world peace. Those who value something strongly will act in accordance with their own code to bring about their ideals, even at the cost of their own self or others. One individual may say that killing is wrong, no matter the circumstances. Another may say that killing to defend the self or the country is not only right, but an obligation. Both of these individuals have a moral code that they follow, but the two moral codes cannot exist at the same time if there is any form of objective morality. Neither of these individuals is incorrect in their beliefs. In many instances, one could argue that because of the vital differences between the two individuals, there can be diversity in thought. Due to this diversity in thought, there can be a radical change in both action and ideas. Thus, the nature of humanity, one of many different ideas and actions, is formed. The only way to create an objective morality is to destroy what most would call the foundation of humanity: the concept of free will.
Free will is a foundation of humanity and is, in some ways, the pillar of ideals. Without it, there would be no differences in mindset, as biology and the mammalian brain would take over. The only other way to destroy the free will of the individual would be to act on the seemingly inherent need for a person to both feel purpose and to seek patterns in life. You could destroy the concept of free will by forcing an individual into a circumstance where they have to complete an assignment that has no creative purpose or reason, such as the destruction of artistic ideas or opposing viewpoints. Once this person is set into that assignment, you must also tell them a series of rules by which to abide at all times. By diverging from these rules, they are not only going against their purpose, but also losing their humanity. You will keep this pattern until the individual believes what you are saying and, once that happens, you reinforce the ideas by giving the individual praise and condemning those who are of a different ideal. If you can do that to every human being on Earth, then you will create an objective morality due to everyone having the same mindset and beliefs. However, you will also remove the fundamental nature of choice from an individual. Some may argue that this is the correct choice, as there would no longer be a need for war or strife and if you gave the individual a purpose that benefits all, many social and world problems (such as famine, poverty, societal isolation, and even the lack of purpose) could be solved.
In closing, the nature of humanity makes the concept of an objective morality impossible without destroying the free will aspect of the human condition. As long as the individual has the capacity to understand and think in their own mind without having that mind molded to a singular purpose, the individual's concepts of what is "right" and "wrong" will be different from others'. Thus, the concept of what is moral will be subjective from one government, society, and individual to another.