FBCOs tend to have mostly middle-class participants because the congregations involved are generally mainline Protestant and Catholic (although "middle-class" can mean different things in white communities and communities of color, which can lead to class tensions within these organizations). Holiness, Pentecostal, and other related denominations (often "storefront") churches with mostly poor and working-class members tend not to join FBCOs because of their focus on "faith" over "works," among other issues. FBCOs have increasingly expanded outside impoverished areas into churches where middle-class professionals predominate in an effort to expand their power to contest inequality.