FOF, I do not think that a person can be regenerated without submitting oneself to Christ and following Him. "There is no other name under heaven given among men whereby we can be saved". I don't see how a person could submit to Christ, if one had never heard of Him....is it absolutely necessary that an individual who truly seeks after God in a real repentance needs to have any special knowledge or understanding of it for it to have its intended affect?
That is not to say that such people will undergo the same degree of corrective judgment which rebels against Christ will undergo. It probably will take very little for many of them to see the Light, in that great day.
On the other hand, some of us may have the same exclusivism within Christianity, that Jews had within Judaism. We may recall that Peter considered gentiles unclean persons who could not be saved. But God showed him through a vision "what God has cleansed, do not call 'unholy'".
Later Peter explained to those who had assembled with Cornelius, "You yourselves understand how out of place it is for a Jewish man to associate with or to approach a foreigner but yet God showed me not to call any person unholy or unclean."
Peter also said, "Truly I perceive that God shows no partiality, but in every nation any one who fears him and does what is right is acceptable to him."
So the words of Peter suggest that a person outside Judaism can "do what is right".
Can the same thing be said about those outside Christianity? Can they avail themselves of the enabling grace of Christ without being aware of the source?
I am inclined to think so. But this is a matter that is not spelled out in scripture, and so I don't want to declare it to be so as if it were a known fact.