[The Urban Sombrero]

You'd have to cite your source for stating categorically that Williams did not wish God's blessing on this land as compared to the nation Israel. I can tell you factually that Williams accepted and understood the concept of the grafted branch, (Gentiles) and he understood that as such we Gentiles are coequal with the nation Israel, Abraham is our father, we are part of His Chosen People and we are numbered among those stars that God Himself showed to Abraham when He sealed His covenant him.
Romans 11:17&24 (KJV)
17 And if some of the branches be broken off, and thou, being a wild olive tree, wert graffed in among them, and with them partakest of the root and fatness of the olive tree;
24 For if thou wert cut out of the olive tree which is wild by nature, and wert graffed contrary to nature into a good olive tree: how much more shall these, which be the natural branches, be graffed into their own olive tree?

But if I have erred in some way please feel free to correct my understanding.

As to salvation, ingrafted branches. As to being the nation through which the lineage of salvation would come, unique. As to Roger Williams, I did not think we were discussing whether or not Roger Williams sought God's blessing upon Rhode Island, though he did seek his guidance in charterting a course toward religious liberty from the state and freedom from coercion by the church.