[prisonchaplain]

I like your definition, of course. But...just what does it mean to say, "all believers?" Believers in Jesus? Believers in our Nicene Creed understanding of Jesus? Believers in the Apostles' Creed? If all who believe in Jesus enter in, does that include subordinationists, such as the Jehovah's Witnesses? What of those who say Jesus alone is God, and that Father and Holy Spirit are just modes Jesus sometimes shows up as (i.e. United Pentecostal Church -- aka 'Jesus Only')?

Then there's the whole matter of the demons believing and being in fear and trembling? So, what level of obedience might we need to see in order to say, "Yeah..s/he really believes with a saving faith?"

IMHO (well...not really so humble), I believe your original answer is basically right, but that the true believer does have some obligation to obey Jesus commands, and to study Scripture so as to better understand the one s/he claims allegiance to.