Many churches, Christian schools, and seminaries have a statement of faith. Usually it's numbered-- starting at one and continuing to the end. Writing down what you believe sharpens your thinking and declares your faith.
Take the next step: order your theology into a series of concentric circles.
By doing so, here are a few extra things you'll discover:
You can apply the ancient creed, "In essentials, unity; in non-essentials, liberty; in all things things, love."
You can distinguish what is absolutely essential and what is not. For instance, most evangelicals believe the Bible is inerrant (without error). But is it necessary to hold that doctrine in order to be saved? I don't think so, and that's why inerrancy isn't in my center core, even though I believe it. Theology in concentric circles helps you decide what matters of faith are truly important.
You can decide what ecumenical activities you can do with other Christians.
For example, if you believe the Bible is without error, can you work with someone who doesn't, yet believes the Scriptures are infallible? Could you participate in a prayer service featuring several different religions, or an inter-Christian one with representatives from liberal and conservative denominations? Concentric circle theology helps you think through such questions.
You can decide the best local church for you to join.
Evangelicals and Pentecostals both believe that faith in Jesus is necessary for salvation. But Pentecostals speak in tongues while many evangelicals do not. What beliefs and practice can you tolerate?
You can discern what's worth fighting for and to what degree.
Martin Luther started the Protestant reformation in the 16th century after becoming convinced that a person isn't made right in God's sight by human works, but by faith alone in Jesus. I'd say that was a doctrine worth haggling over.
You can prevent your faith from tumbling over like dominoes.
If the resurrection of Jesus isn't real, our faith is vanity, says Paul in 1 Corinthians 15. That's a core issue. But doubts about the composition of John's Gospel, how the end times unfold, or other matters related to faith need not cause you to throw in the towel. Theology is important, but not every aspect is an "all or nothing" proposition.