First, we need to understand the kind of belief that's relevant to the question. When the New Testament speaks of belief of the sort that's in view here (Koine: pistis), it's referring to a persuasion. In other words, belief (i.e. faith) is quality of certainty regarding a proposition: for instance, "God exists." Hebrews 11:1 (ESV) describes it as such, "faith is the assurance of things hoped for, the conviction of things not seen." So belief is a state of certainty about things that can't be seen.
When we add the parameter of belief according to the standard of the Bible, a rather clear picture emerges.
Let me lay out on a scale which builds this standard from the most fundamental and necessary to the least. Only one who believes according to the entire scale could truly be called a Bible-believing Christian, anything less would call into question the genuineness, according to the biblical measure, of such a person's faith. Will people who believe less than the whole scale be saved? Yes, I think that is possible, but they will be weak in faith and limited in their growth into Christ.
- Jesus rose from bodily from the dead
- Jesus is the Son of God, that is, God with us
- Jesus is our leader, unquestioned, as is everything he taught and said
- The Old Testament is true, every jot and tittle
- Moses was an actual deliverer, the Exodus an actual migration
- Noah was an actual person, the Flood an actual event
- Adam and Eve were actual persons, the Creation Week an actual occurrence
