There are three important names in the lessons for Sunday (two explicit, one contextual).
Abram becomes Abraham - the exalted father of many nations
Sarai become Sarah - the princess mother of many kings
Napthali became Caeserea Philippi - Caeserville in the land promised to God's chosen people (the place where Peter calls Jesus "Messiah" and then tries to begin a revolution)
It is a little known (and less often used) historical fact that names can be changed at baptism and at ordination (there may be other times that I am not aware of). Abraham and Sarah have their names changed by God because their relationship is changing. So too can we have our names changed when the rules by which we choose to play change.
Stalingrad is once again St. Petersberg - the rules changed. For Peter, Caeserea needed to return to Napthali, but Jesus knows that isn't going to happen because this rule change is much larger than revolution and political power. This new set of rules is the installation of the kingdom of God. Names may change, but it is the hearts that change that matter.
Abram wouldn't become Abraham without faith. Sarai wouldn't become Sarah without faith. And we don't become Christians without faith.
Name changes are important, but more important is why the change happened.