The HEbrew Bible does not say only Abraham believed in G-d as the Most High
G-d. It is unlikely that he would give a tithe to a priest of a different
Most High G-d that he called by G-d's name to show who he was really donating
to. Maybe you have heard about people called the sons or children of Noah or
Noahides. They believe that Noah taught the world to believe in G-d and that
Abraham was not the only one.
Now that I have given an opinion, I guess this thread will be closed to
prevent any further religious discussion.