We do, however, come from different theological traditions, some of which result in us believing different things about God and about the world.
Those in the Reformed tradition (Presbyterians fall in this category) believe in the sovereignty of God. Almost all major doctrines and beliefs we hold come back to this: God is God. God is in charge. We are not God. Believing that God is sovereign affects the way we talk about salvation, the Christian life and even what a pastor does.
What we believe doesn't just affect church-y things. Believing that God is sovereign also means that I do not believe rich people deserve to be rich or poor people deserve to be poor. I believe that the life we were born into is out of our own control, which affects the way I view individual and systemic economic struggles.
Beliefs about God and the world are not just for those in church. We all have them, whether we acknowledge it or not. With other Christians, I have the opportunity to engage what I believe with what is going on around me and seek to follow God's will in everything I do. That's one reason I go to church.