Thats incorrect.Of course the disciples were to write down what Jesus said.And of course John was sinful.All men are sinful,even Mohammed.
The Islamic Evidence
We now present the Islamic data showing that Aisha was a girl of nine when Muhammad consummated his marriage to her. All bold, capital and underlined emphasis is ours.
SAHIH AL-BUKHARI
Narrated Aisha:
The Prophet engaged me when I was a girl of six (years). We went to Medina and stayed at the home of Bani-al-Harith bin Khazraj. Then I got ill and my hair fell down. Later on my hair grew (again) and my mother, Um Ruman, came to me while I was playing in a swing with some of my girl friends. She called me, and I went to her, not knowing what she wanted to do to me. She caught me by the hand and made me stand at the door of the house. I was breathless then, and when my breathing became all right, she took some water and rubbed my face and head with it. Then she took me into the house. There in the house I saw some Ansari women who said, "Best wishes and Allah's Blessing and a good luck." Then she entrusted me to them and they prepared me (for the marriage). Unexpectedly Allah's Apostle came to me in the forenoon and my mother handed me over to him, and at that time I was a girl of nine years of age. (Sahih Al-Bukhari, Volume 5, Book 58, Number 234)
Narrated Hisham's father:
Khadija died three years before the Prophet departed to Medina. He stayed there for two years or so and then he married 'Aisha when she was a girl of six years of age, and he consumed that marriage when she was nine years old. (Sahih Al-Bukhari, Volume 5, Book 58, Number 236)
Narrated 'Aisha:
Allah's Apostle said to me, "You were shown to me twice (in my dream) before I married you. I saw an angel carrying you in a silken piece of cloth, and I said to him, 'Uncover (her),' and behold, it was you. I said (to myself), 'If this is from Allah, then it must happen.' Then you were shown to me, the angel carrying you in a silken piece of cloth, and I said (to him), 'Uncover (her), and behold, it was you. I said (to myself), 'If this is from Allah, then it must happen.'" (Sahih Al-Bukhari, Volume 9, Book 87, Number 140; see also Number 139)
Narrated 'Aisha:
that the Prophet married her when she was six years old and he consummated his marriage when she was nine years old, and then she remained with him for nine years (i.e., till his death). (Sahih Al-Bukhari, Volume 7, Book 62, Number 64; see also Numbers 65 and 88)
SAHIH MUSLIM
'A'isha (Allah be pleased with her) reported: Allah's Messenger (may peace be upon him) married me when I was six years old, and I was admitted to his house at the age of nine. She further said: We went to Medina and I had an attack of fever for a month, and my hair had come down to the earlobes. Umm Ruman (my mother) came to me and I was at that time on a swing along with my playmates. She called me loudly and I went to her and I did not know what she had wanted of me. She took hold of my hand and took me to the door, and I was saying: Ha, ha (as if I was gasping), until the agitation of my heart was over. She took me to a house, where had gathered the women of the Ansar. They all blessed me and wished me good luck and said: May you have share in good. She (my mother) entrusted me to them. They washed my head and embellished me and nothing frightened me. Allah's Messenger (may peace be upon him) came there in the morning, and I was entrusted to him. (Sahih Muslim, Book 008, Number 3309; see also 3310)
'A'isha (Allah be pleased with her) reported that Allah's Apostle (may peace be upon him) married her when she was seven years old, and he was taken to his house as a bride when she was nine, and her dolls were with her; and when he (the Holy Prophet) died she was eighteen years old. (Sahih Muslim, Book 008, Number 3311)
Muhammad's Marriage to a Prepubescent Girl and its Moral Implications