Presbyterian are the way we are because Presbyterians are Christians who believe:
Studying the bible prayfully and together helps us figure out which things matter more than other things; Grace happens; God's grace invites response; God gives us brains and expects us to use them. We ar beloved, gifted, capable, and safe. Already, Right now; God calls us to be on the side of the ones who are having the hardest time; Nobody's perfect; There's more Holy Spirit in a bunch of us than in any single one of us; God isn't finished; and God's love is not limited to our particular faith community.
As can be found on the Presbytery PC USA website