In the United States, we've worked hard to protect the practice of Religion--which, until recently, was Protestant Christianity. Catholicism wasn't fully accepted until the time of the Kennedy Presidency in the 60s.
Non Christian religions have been culturally discriminated against, but have been constitutionally protected--even atheists. The only groups that have lost this protection are those that break the laws--especially if it leads to violence.
Over here, you'd be very unwise to refer to Christian Religious groups as sects