Why should we expect them to be coherent? Our lives rarely are, so why should the lives of the ancients be different? Most people's theology is created on an "as needed" basis, just like it was back then. If it works, great.
Mind you, I'm not endorsing that mindset! I agree with Socrates that the unexamined life isn't worth the living; but I also realize I'm in the minority there. And my life isn't always coherent! My life and theology are a work in process.