The Southern Poverty Law Center (SPLC) is one of the most respected and credible organization in the US. It does not discriminate when it comes to identifying Hate Groups.

So when it says that Act for America (founded by Brigitte Gabriel) as an "an anti-Muslim hate group" it perfectly describes said organization.

"The SPLC monitors the "activities of domestic hate groups and other extremists – including the Ku Klux Klan, the neo-Nazi movement, neo-Confederates, racist skinheads, black separatists, antigovernment militias, Christian Identity adherents and others".

https://www.splcenter.org/hatewatch/2017/06/10/live-blog-act-america%E2%80%99s-%E2%80%9Cmarch-against-sharia%E2%80%9D-rallies-1