Religion in God has been a major aspect of human civilization for centuries and defines cultures, traditions and moral systems in the world. This is however not shared by everyone. Increasingly, people are turning out to be non-believers, influenced by various philosophical, scientific, and personal views. The reason why not all people believe in God cannot be answered without a careful and objective study of their arguments, without prejudice and bias. Such views usually have their basis in intellectual inquiry, life experiences, and the changing worldview and are a manifestation of the diversity of human thought in a fast-evolving world.
The Impact of Scientific Knowledge

Scientific discovery is one of the most prevalent factors that drive people out of belief in God. With the spread of scientific knowledge, most people discover that natural explanations of the universe, life and human existence lessen the necessity of having a divine explanation. The ideas of evolution, cosmology, and physics provide elaborate structures that explain the phenomena, which were initially blamed on divine intervention. The use of evidence-based reasoning renders faith-based belief redundant or unrelated to the way some people perceive the world.
The Inequality and Pain of Suffering

Suffering, injustice, and hardship in the world usually make people doubt the existence of the benevolent and all-powerful God. Once people are exposed to or encounter severe pain, either by personal tragedy or world disasters, they can find it difficult to square these facts with the belief in a caring supreme being. This philosophical quandary, also known as the problem of suffering, can play a major role in influencing unbelief among many.
Lack of Empirical Evidence

Certain people put more emphasis on evidence that can be seen, experimented, and proven. In this light, God is not empirically supported as is expected with any claim to declare it true. In the absence of physical evidence, these people might perceive religious beliefs as hypothetical, and not as factual. This method is frequently based in critical thinking and intellectual coherence in every aspect of belief.
Cultural and Environmental Factors

Cultural and social environments have a great impact on belief systems. Individuals who grow up in secular families or communities where religion does not play a significant part tend to avoid developing an attitude towards God. In these settings, non-belief is usually the default and not an active rejection. When individuals are exposed to different worldviews, they can also develop an interest in doubting what was passed on to them and embrace a worldview that is more suitable to their environment.
Philosophical views on reality

Philosophy is the important part of the beliefs on existence and the nature of reality. Other philosophical systems focus on naturalism that postulates that all things can be elucidated by natural factors without supernatural factors. Others consider existential questions that look at the human meaning and purpose without mentioning the existence of a divine being. Such views offer other approaches to the understanding of life that do not depend on the belief in God.
Suspicion of Organized Religion

To others, the lack of faith in God is much related to doubt of organized religion. The lack of trust can be caused by historical events, institutional scandals, and the perceived discrepancies with religious institutions. By identifying belief in God with systems that people perceive to be flawed or problematic, they can end up shunning not only those institutions but also the belief itself.
Personal Experiences and Life Events

The individual beliefs of an individual can be as well affected by personal experiences. The dark times, prayers left unanswered, or the absence of spiritual connection can make some doubt their faith. On the other hand, those who have never had a feeling of divine presence might not easily believe in the first place. Such autobiographical accounts tend to influence the long-term views in substantial ways.
Emphasis on Human Responsibility

Other individuals tend to consider human agency and responsibility instead of the higher power as the cause of the outcomes. This school of thought lays stress on the fact that the future of individuals and societies is in the hands of individuals and societies. Without the notion of some godly intervention, human beings can experience enhanced responsibility in their actions and choices.
Introduced to Varying Belief Systems

With the current globalized world, people are exposed to diverse religious and non-religious beliefs. This disparity may raise questions about which, or none, of the systems of thinking is right. In a situation where there are several and sometimes opposing points of view, certain individuals find themselves with the conclusion that none of the points is absolutely true and thus they assume a non-belief or skeptical stand.