 The migrations and missionary efforts of each of these groups lead to the widespread significance of the Westminster Assembly throughout the English @-@ speaking world . The Assembly 's Confession was particularly influential in American Protestant theology . It was included with congregationalist changes as part of the 1648 Cambridge Platform , a statement produced by ministers of colonial Massachusetts and the surrounding region , and again in colonial Connecticut as part of the 1708 <unk> Platform . The Confession was modified for American Baptists in the <unk> Philadelphia Confession . The <unk> Act of <unk> required American Presbyterians to agree to the theology of the Assembly 's Confession , and the Confession remains a part of the Presbyterian Church ( USA ) ' s Book of Confessions . The Confession has been called " by far the most influential doctrinal symbol in American Protestant history " by the historian of religion Sydney E. <unk> . 
