Why was it so special that John the baptist was not called Zechariah?

I think we should more carefully read the Gospel (Luke 1:59-66):

And it came to pass, that on the eighth day they came to circumcise the child; and they called him Zacharias, after the name of his father. And his mother answered and said, not so; but he shall be called John. And they said unto her, there is none of thy kindred that is called by this name. And they made signs to his father, how he would have him called. And he asked for a writing table, and wrote, saying, his name is John. And they marvelled all. And his mouth was opened immediately, and his tongue loosed, and he spake, and praised God. And fear came on all that dwelt round about them: and all these sayings were noised abroad throughout all the hill country of Judaea. And all they that heard them laid them up in their hearts, saying, what manner of child shall this be!

People was so surprising, "marvelled all", because Zacharias advertises to people (maybe by the signs if he could not speak yet) that his child already had the name which was previously given by God through the Angel Gabriel (Luke 1:13):

But the angel said unto him, fear not, Zacharias: for thy prayer is heard; and thy wife Elisabeth shall bear thee a son, and thou shalt call his name John.

ADDITION:

A little different interpretation was given by Saint Theophylact of Ohrid (1055–1107) who wrote (sorry, I can not find free english translation) in "The Explanation of the Holy Gospel":

Захария, не будучи в силах объявить им знаками, просит дощечку; и когда он относительно имени дитяти оказался совершенно согласен с женой, «все удивились», ибо не было сего имени в родстве их, и никто не мог сказать, что оба они уговорились об этом еще прежде времени.

This means that Saint Theophylact thinks that Zacharias and Elisabeth can not talk to each other (Zacharias by the signs because he could not speak) about a name of their child and people knew about it, so were surprised by the coincidence of names happened by God's Providence and the fact that the child's name was not selected from the genealogy of parents.

There are two facets to the naming of John.

One the surprise, the thing that made the naming special, is really that the father Zacharias agreed with the mother Elizabeth about her naming their son John.

The "right" to name a child in a patriarchal and/or Jewish society fell to the father. This harkens to Abraham naming Isaac on the 8th day (circumcision).

And God said [to Abraham], Sarah thy wife shall bear thee a son indeed; and thou shalt call his name Isaac: ... And Abraham called the name of his son that was born unto him, whom Sarah bare to him, Isaac. Gen 17:19, 21:3

Two as to why the name John was used, the name John means God is Gracious. John introduced Messiah who would die for the sins of the world, be buried, and rise again the 3rd day for our life; He delivers us.

Thus, God's grace led to, introduced Jesus who delivers us.

For the most part, the tradition would not be to name a child after the father and so in 2 Chronicles you don't find boys named after their father's. Consider the Patriarchs: Abraham, Isaac, Jacob and Joseph. All additional examples that a son is not named after a father.

However, sons may well be named after relatives (depending on the specific tradition the relatives may be living or may be deceased); but nonetheless the child is always associated with the father's name in this way:

Joseph bar Jacob.

This would be Joseph, son of Jacob; not Jacob II or Jacob Jr.

In this light, the surprise about John's name is in fact because there aren't any relatives named John. And to add a bit of extra interest, consider that John never became known as John bar Zechariah but became John the Baptist.

"Patronymy" is the term for giving the first name of a son the name of the father. "Papponymy" is the term for giving a newborn son the first name of the paternal grandfather.

Papponymy is found in the High Priestly line with Onias I being the father of Simon I, the father of Onias II, the father of Simon II, the father of Onias III. Patronymy is found in that the son of Onias III was Onias IV.

Another example, though not certain, may be the case of Ahimelech whose father was Abiathar (2 Sam 8:17) who was named after Abiathar's father Ahimelech (1 Sam 22:20).

I believe the story of the giving of the name of John (later John the Baptist) by his parents gives evidence that either papponymy or patronymy was the common practice amongst the Levites of the era.

Why was it so special that John the baptist was not called Zechariah?

First of all, John and not Zechariah was the name to be given to Elizabeth’s new born.

Let us now look at what St. Luke writes about the birth of John the Baptist:

11 Then an angel of the Lord appeared to him, standing at the right side of the altar of incense. 12 When Zechariah saw him, he was startled and was gripped with fear. 13 But the angel said to him: “Do not be afraid, Zechariah; your prayer has been heard. Your wife Elizabeth will bear you a son, and you are to call him John. 14 He will be a joy and delight to you, and many will rejoice because of his birth, 15 for he will be great in the sight of the Lord. He is never to take wine or other fermented drink, and he will be filled with the Holy Spirit even before he is born. 16 He will bring back many of the people of Israel to the Lord their God. 17 And he will go on before the Lord, in the spirit and power of Elijah, to turn the hearts of the parents to their children and the disobedient to the wisdom of the righteous—to make ready a people prepared for the Lord.”

18 Zechariah asked the angel, “How can I be sure of this? I am an old man and my wife is well along in years.”

19 The angel said to him, “I am Gabriel. I stand in the presence of God, and I have been sent to speak to you and to tell you this good news. 20 And now you will be silent and not able to speak until the day this happens, because you did not believe my words, which will come true at their appointed time.”

21 Meanwhile, the people were waiting for Zechariah and wondering why he stayed so long in the temple. 22 When he came out, he could not speak to them. They realized he had seen a vision in the temple, for he kept making signs to them but remained unable to speak.

23 When his time of service was completed, he returned home. 24 After this his wife Elizabeth became pregnant and for five months remained in seclusion. 25 “The Lord has done this for me,” she said. “In these days he has shown his favor and taken away my disgrace among the people.” - Luke 1:5-25

Now we can deduce from the Sacred Scriptures that the emphasis should be on the name given to Elizabeth’s new born given to Zechariah by the Angel of God and not on his own name or one of his kinship as was traditional done.

Either name could have been give to the Forerunner of Jesus, but God willed that his name be John and Zechariah seconded God’s will!

Perhaps God did not desire the name of the Baptist to bare any association to his earthly family, but wanted it to reflect more his own divine intentions.

Any real reason for why God chose the name of John over Zachariah is not truly known to us and remains a mystery and is speculative at best.

John

English form of Iohannes, the Latin form of the Greek name Ἰωάννης (Ioannes), itself derived from the Hebrew name יוֹחָנָן (Yochanan) meaning "YAHWEH is gracious", from the roots יוֹ (yo) referring to the Hebrew God and חָנַן (chanan) meaning "to be gracious". The Hebrew form occurs in the Old Testament (spelled Johanan or Jehohanan in the English version), but this name owes its popularity to two New Testament characters, both highly revered saints. The first is John the Baptist, a Jewish ascetic who is considered the forerunner of Jesus. He baptized Jesus and was later executed by Herod Antipas. The second is the apostle John, who is traditionally regarded as the author of the fourth gospel and Revelation. With the apostles Peter and James (his brother), he was part of the inner circle of Jesus.

Zechariah

From the Hebrew name זְכַרְיָה (Zekharyah) meaning "YAHWEH remembers", from זָכַר (zakhar) meaning "to remember" and יָה (yah) referring to the Hebrew God. This is the name of many characters in the Old Testament, including the prophet Zechariah, the author of the Book of Zechariah. The name also appears in the New Testament belonging to the father of John the Baptist, who was temporarily made dumb because of his disbelief. He is regarded as a saint by Christians. In some versions of the New Testament his name is spelled in the Greek form Zacharias or the English form Zachary. As an English given name, Zechariah has been in occasional use since the Protestant Reformation.

The OP asks: "Why was this so surprising, because in the lists of names in the bible, I do not find people having the same name as their father?"

The text of Lk. 1:58-61 says:

Her neighbors and kinsfolk heard that the Lord had shown great mercy to her, and they rejoiced with her. And on the eighth day they came to circumcise the child; and they would have named him Zechari′ah after his father, but his mother said, “Not so; he shall be called John.” And they said to her, “None of your kindred is called by this name.”

The OP is correct that a Jewish boy would not normally be named after his father. There is no instance of this occurring anywhere in the Bible and it is not normally done in Jewish families to this day. There were a few exceptions, however, in later generations. Naming a child after a grandparent, on the other hand, is not so rare. There are known cases at the time in question: Gamaliel II was the grandson of Gamaliel the Elder, who is know to Christians from Acts 5.

So the neighbors should not have been surprised that John was not named after Zechariah. On the other hand, the objection that "none of your kindred is called by this name" does makes sense, as Jews often did name their children after a recent relative of a previous generation. We are left with two possibilities. Either:

1. This was a special case. There must have been a local naming tradition in the area where John was born, or possibly the expectation was due to the miraculous conception of the child and the fact Zechariah was easily old enough to be John's grandfather.

2. Luke's report is based on erroneous information. He admits his information was "delivered to us by those who from the beginning were eyewitnesses." (Lk. 1:2) However, by the time Luke wrote (around 80 c.e.) reliable eyewitness to this event would already be dead.

The decision as to whether it was a special case or an erroneous report is related to the question of whether the Bible can ever report something that is not factual, even if the report is faithfully recorded by the author. Those who hold strictly to biblical inerrancy must deny this possibility and opt for the "special case" scenario. Those who are open to the a 'faithful but incorrect' report may choose the explanation that Luke's information here, though correctly reported, was faulty.

I'd like to suggest it has much deeper meaning than most have considered. Names are, indeed, very important in the Bible. When one hears the name "John" in terms of the Bible, there are 2 John's that come to mind instantly. This conection, I believe, must be intended. It is interesting that John, the apostle, quotes many times from the Book of Zechariah...now where have I heard that name before? ;) Why does it matter? Well, for eschatological reasons, as John the apostle was chosen to write the Book of Revelation in which he describes the events leading up to Christ's second advent. Who was it that spoke of Christ's first advent? Yes, the other John. One more connection and I will leave you to prayerfully consider what I have shared. John Baptist was the "Elijah forerunner" of Christ's first advent, and there is another "Elijah" forerunner expected "before the great and terrible day of YHVH"...in the Book of Rev., John states, "I John, your brother and fellow participant in THE [emphasis mine] Tribulation..." "Word play" is common throughout the Scriptures, and it seems to me this can't be "coincidence." The John-John link was intentional to connect the "Elijah forerunner" to the Book of Revelation. My thoughts. shalom