Do not think that knowing the beginning of the gospel is a minor thing. God is perfect and does not leave to chance a thing like the beginning of the gospel.
In order to understand the importance of this, we must remember that the gospel ("ευαγγέλιο" in Greek) means “the Good News” of our salvation, our redemption from the eternal sadness of sin.
Many believe that the answer is simple: the Gospel begins with the first book of the New Testament and the first verse (that is, Matthew 1: 1) but, if we read there, we see that it is written, “The book of the generation of Jesus Christ, the son of David, the son of Abraham.”
If we want to research the theological masterpiece of the New Testament—the Gospel of Saint John—we see that, in the first verse, is written, "In the beginning was the Word, and the Word was with God, and the Word was God."
Turning to Saint Luke, whose gospel is the most documented and most literary, we see that it begins with, "Forasmuch as many have taken in hand to set forth in order a declaration of those things which are most surely believed among us, even as they delivered them unto us, who from the beginning were eyewitnesses and ministers of the word, it seemed good to me also, having had perfect understanding of all things from the very first, to write to you in order, most excellent Theophilus, that you might know the certainty of those things, wherein you have been instructed."
There is still Saint Mark, who really begins with, "The beginning of the gospel of Jesus Christ, the Son of God." Why has the Holy Spirit made the things to be in such a way?
Why? Because Saint Mark begins immediately with the baptism of repentance that Saint John the Baptist did for the forgiveness of sins. Saint John even emphasized, "Repent, for the kingdom of heaven is at hand!" After Saint John the Baptist was thrown into prison, Jesus came and began his activity with exactly the same words "Repent, for the kingdom of heaven is at hand!"
So the beginning of the gospel—the beginning of our salvation from eternal existential torment—is repentance.
Okay, but what is repentance?
Every person, being intelligent, has free will—so that person has the opportunity to depart from the right way to be (from the right path), to enter into sin and to distort his existence.
It's like a car that entered the ditch. Repentance means the realization that “I cannot get out of the ditch alone. So, I need to call a crane to lift me out of there. Thus, I may be able to work with the crane to free me from the ditch and continue my journey.”
The special service, through which we show our willingness to repent, by which we cry out more to God to remove us from the ditch, is the Great Canon of Repentance of Saint Andrew of Crete, which is held at Vatopedi Monastery on the evening of Wednesday, 1st of April, 2020, at 21:00, Athens time. If you would like to join us, you have the following link the Great Canon of Repentance.
In the photo, a priest from the Vatopedi monastery, Mount Athos praying for the rescue from the pandemic.