The second is to believe the Gospel...
The second is to believe the Gospel, that is, the message that God’s kingdom was about to penetrate the Roman Empire. The word translated “repent” is metanoeite which comes from metanous. Just as metaphysics goes beyond the physical to the matters of the mind, this “metanoia” goes beyond the matters of the mind.
In other words, Jesus (AS) appears to be telling the people not to be deceived by what they see and think, but to go beyond that to realize something that their minds could not tell them, that what he is saying is true, that God is about to set up His kingdom. The clear inference is that despite the situation and what it seems to be, they owe their ultimate allegiance to God. The next text is in Mark 16:15,16.
“And he said unto them, Go ye into all the world, and preach the gospel to every creature. He that believeth and is baptized shall be saved; but he that believeth not shall be damned.” This text does not give more detail about the content of the message at all. It refers to the delivering of the message, and the results of it. Some will believe and be saved, and others will not believe, and be damned.
That is, some will realize that they owe ultimate allegiance to God, and believing that, they may be saved. Others will deny obedience to the sovereignty of God, and consequently will be lost. An interesting point is that baptism is mentioned along with belief as one of the requisites for being saved. Baptism is not very well defined in the New Testament either. It arose out of the Jewish practices of ablutions, in two contexts.
The one was conversion to Judaism, and the other was the baptism of repentance, such as that represented by John. The baptism which came into use among the early followers of Jesus (as) doubtlessly included those characteristics, and apparently more as well. But whatever it meant, it was clearly within a purity code with a practice of ablutions.
Furthermore, whatever it meant, it was not a part of the proclamation of the Gospel, but a result and response to it, one coupled with belief in the sovereignty or “kingdom” of God. Baptism is the first matter that is associated with the Gospel in this text, but it is not the only one. If it is intrinsic to the Gospel proclamation itself, then the issues in the following texts are as well.