There's lots of scriptures which could have been drawn upon. We all fail as Christians (especially me) in knowing the right thing to say at the right time. But one would hope our spiritual leaders could clearly articulate the Christian message through the written word.
Only protestants do that. Catholics and orthodox approach the matter a little differently. To be truthful, I don't know what gospel they preach. It used to be the gospel of membership in their church along with being at least being nominally catechized and the sacraments, which does presuppose correct belief in Jesus as savior.
The early Christians were converted through testimony and being pointed to a structured church (although more loosely structured than the monolithic western model we have now), baptism, sacraments, etc., with little drawing on the word because they didn't have a new testament as we know it now. I think, to be fair, they have tended to follow that model throughout history more than relying on the written word alone for purposes of conversion.
Drawing from the scriptures has gained a lot of converts since the invention of the printing press and the education of the masses who can read them for themselves as they were unable to do for centuries. It is fraught with some obvious difficulties as few are in absolute agreement about the scriptures really mean and how they should be correctly interpreted.
Personally, for now, I accept both systems of belief if one is doing the best they know how to follow Jesus and what they understand of his teachings.