Sir Brennen said:
Scientology is not promoted as a religion in many other countries in which it operates, but is merely a "consulting group". It is widely believed that Scientology established itself in the US as a "religion" mainly for tax purposes.
That and so they would not be prosecuted for practicing medicine without a license. In the 1950's the early Dianetics and Scientology Franchises (they weren't called "Churches" yet) were investigated heavily by the FDA and the AMA, and they were accused of practicing medicine without a license, since their "self help" programs and "auditing" counseling were touted as being able to cure cancer, migraines, broken bones, and countless mental disorders. The "past life" aspects of their regression therapy had religious connotations, so they would pull them out when investigation got too hot. When psychiatrists started seriously questioning (and outright debunking) their claims, they founded the "Citizens Commision on Human Rights" as their anti-psychiatry "watchdog" group and began a decades long campaign to eliminate all psychiatry.
This was instantly controversial, and after a long, drawn out fight in 1967 the IRS revoked their Tax Exempt status, saying their religious claims were a sham. This was about the same time they were found by a court in the UK to not be a legitimate religion, so they moved into international waters aboard a small fleet of ships and L. Ron titled himself "The Commodore" and ran the CoS from the ocean for the rest of his life. They also began suing the IRS with literally thousands of lawsuits over their tax-exempt status. This lead to a series of court fights where the in 1993 (a 26 year court battle) the IRS finally settled with the CoS in a sealed settlement where the IRS would grant tax-exempt status, in exchange for dropping their lawsuits (and some other concessions that both parties agreed to keep secret, and the IRS hasn't disclosed the full terms of the settlement, even in violation of a court order and tax law).
In 1971 a US court ruled that their medical claims were completely bogus, so they responded by completely incorporating as a religion and "fees" became "fixed donations", auditing was "pastoral counseling" and "confession", quack medicine overdoses of vitamins went from being "detoxification" to a "religious sacrament". "Franchises" became "Missions" and "Churches". Senior staff members occasionally wore clerical collars too. Nothing changed about their procedures, just the terms they used. L.Ron's space opera cosmology became "sacred scriptures".
The tax exempt status is awfully nice (and it gives a legal degree of respectability to their religious status), but Scientology practices would have been banned in the US over 30 years ago as quack medicine if they didn't claim that their treatments were religious practices. You have to really question a "religion" where not only do you have to pay big bucks for their religious texts and to find out what they actually believe (virtually every other religion is happy to give you a copy of their holy books and teach you what they believe for free), but actively and aggressively prosecutes those who practice their teachings or spread their "scriptures" without their permission for copyright problems, trademarked the name of their "religion" and claims legal "Trade Secret" protections on many of their "scriptures".
In many countries, they don't even claim to be a religion, it's just a nice convenience that in the US if you call it a religion you can get away with an awful lot because of our traditional national tolerance towards unorthodox beliefs and strong constitutional protections. In Israel they offer the exact same services as a secular philosophy/self-help group and make no claims of being a religion.