The "light" also referred to as the "lessor light" doctrine does not just apply to those pre Azusa, it applies to everyone post day of Pentecost.
It simply states that all who are "believers" are accepted by God in what ever light they have received, (but they must walk in all of the light they have received) an that while they are in the "lessor light" it should lead them to the full light of
Acts 2:38.
If this doctrine is correct then we have no reason to evangelize our world with the "full" light. We might as well join hands with our trinitarian "brethren" and win the world to whatever light they will accept, because in essence we will all get the same reward anyhow.