Because the United States Constitution bars Congress from passing any law infringing upon religion, new religions do not have an official registry. However, the IRS grants tax-exempt status to qualifying organized churches that meet specific guidelines under section 501(c)3 of the Internal Revenue Code.
The first step for setting up a new church in the eyes of the IRS is establishing it as a 501(c)3 organization. According to the IRS website, an organization must operate only for specified exempt purposes and not pay its earnings or profits to private individuals or other shareholders (this does not include salaries, only profits). Because the paperwork is complex and making a mistake could result in a very expensive audit, it is smart to hire a lawyer specializing in setting up tax-exempt organizations before filing this paperwork.
The IRS is guided by special laws regarding religious organizations. For example, the IRS is barred from random audits of churches; instead, high-level treasury officers must reasonably believe that a church is engaging in activities not approved for tax-exempt organizations in order to initiate an audit. They are very aware that some people attempt to use churches as a way to fraudulently profit or avoid taxes. For this reason, churches undergo extra scrutiny that is likely to bring such activity to light.