The freedom of religion (the freedom to have, not to have, to practice, or not to practice any religion) is a fundamental right—under both the U.S. constitution and international law. For this reason, victims of religious persecution are entitled to certain protections under U.S. immigration law. If you have been persecuted, or if you fear being persecuted in your home country because of a religion (because you have or lack, or you are perceived to have or lack, a religion), then you might qualify for asylum or refugee protection in the United States. Such status would allow you to live and work in the country, and would make you eligible for permanent residence (the green card) after one year.
This article discusses what the law counts as "religion," what it counts as "persecution," and how to prove that religion is the cause for persecution in particular cases, when applying for U.S. asylum or refugee status.
There is no exclusive definition of religion under U.S. law. Any such definition would risk running counter to the principle of religious freedom, by marginalizing worldviews that are in the minority. Instead, the term "religion" must be understood broadly to include not only traditional institutionalized religions like Hinduism, Judaism, Buddhism, Christianity, or Islam, but also any other newer or smaller system of sincere beliefs or practices that plays a similar role in the life of its adherents (whether or not it is associated with a God or gods).
This means that, if you belong to a religious minority in your home country (be it because of your unusual personal views on one or more religions, or because of your membership in a small or little-known religious sect), you should not hesitate to seek protection in the U.S. for the persecution you might suffer or have already suffered on account of the fact that your beliefs were not recognized by others in your home society. On the contrary, it is often for people in your position that religious asylum and refugee protections tend to be especially appropriate.
This does not mean, however, that sticking the label "religious" to just any set of beliefs or practices whatsoever would be acceptable. Rather, what the U.S. government recognizes as a religion will be determined on a case-by-case basis. So, if the religion you intend to base your asylum or refugee claim upon is not well known, it would probably be a good idea to try to highlight parallels between your beliefs or practices (or those of your persecutors) and those of more "established" religions.
(Note: Sometimes religious identity overlaps with national and other group identities. In such cases, asylum or refugee status applicants may base their claim on more than one ground.)
For purposes of U.S. asylum or refugee status, the word "persecution" generally refers to serious threats or inflictions of physical, psychological, or economic harm by one's own government or by groups whom one's government is either unwilling or unable to control.
Thus, if you have been beaten, detained, or otherwise individually punished by a religious police—or even by a family member whose authority over you is recognized or tolerated by your country's government—based on your supposed failure to comply with religious norms (for example, a dress code, such as the requirement that women wear a veil covering their face and chest), then you might qualify for religious asylum or refugee protection in the United States.
In addition, you might claim religious persecution even when you have not been individually targeted, if your country's laws impose special restrictions on your religious freedom (say, by forbidding membership in your religious group, by limiting public worship, or by requiring conversion to any other faith), and those laws have a serious impact on your individual way of life. If, for example, you were raised Catholic in China, but you are not currently observant, then you would have a harder time proving that you were harmed if the country's government were somehow to pass a law forbidding church attendance.
At the same time, laws that have a neutral or otherwise legitimate purpose but happen to be more harmful to particular religious groups might not be considered persecution (unless they are enforced unequally). For example, a public health law prohibiting all possession of a mind-altering substance that one religious group uses in its rituals would probably not provide a basis for asylum or refugee status. By contrast, a law compelling military service without exemptions for conscientious objectors might well qualify.
To obtain U.S. asylum or refugee protection, it is not enough to prove that you have or lack (or that you are perceived to have or lack) a particular religion, and that you have been or may be persecuted in your home country. Rather, you must make clear that your actual or perceived lack of religion is the main reason (or one of the main reasons) for your persecution.
Proving this link can be difficult. For example, if you are part of a group of Christian missionaries working in a disputed region of your home country during a civil war, and government forces regularly beat and detain members of your group for purposes of obtaining information about rebel forces, then arguing that your religion is the reason why you were beaten or detained might be more difficult than you think. (You might consider a claim based on political opinion instead.)
An immigration attorney would help make sure you are applying under the appropriate category, and could significantly improve your application's chances of success.