{The beginning} (arch(885c)). There is no article in the Greek.
It is possible that the phrase served as a heading or title for
the paragraph about the ministry of the Baptist or as the
superscription for the whole Gospel (Bruce) placed either by Mark
or a scribe. And then the Gospel of Jesus Christ means the
Message about Jesus Christ (objective genitive). The word Gospel
here (euaggelion) comes close to meaning the record itself as
told by Mark. Swete notes that each writer has a different
starting point (arch(885c)). Mark, as the earliest form of the
evangelic tradition, begins with the work of the Baptist, Matthew
with the ancestry and birth of the Messiah, Luke with the birth
of the Baptist, John with the Preincarnate Logos, Paul with the
foundation of each of the churches ( Php 4:15 ). {The Son of God}
(Huiou theou). Aleph 28, 255 omit these words, but B, D, L,
have them and the great mass of the manuscripts have huiou tou
theou. If this is a heading added to what Mark wrote, the
heading may have existed early in two forms, one with, one
without "Son of God." If Mark wrote the words, there is no reason
to doubt the genuineness since he uses the phrase elsewhere.