One thing about being a Baptist that was always taught is that historically we agreed on one principle (to quote James Dunn): "Ain't nobody but Jesus gonna tell me what to believe." Which is to say that there is no litmus test for faith. There is no one principle you have to agree to in order to get into the club of Christianity. But that's not entirely true. There is one, and it's the only one I'll acknowledge.
“Love your neighbor as yourself.”
In an article on Baptist News Global, Seth Vopat agrees, and explains what that really means. It's both easier and harder than it seems.