Is there scripture that states that a child must be christened/baptized in order to enter into heaven?


No, in fact it is not scriptural at all. We have numerous instances of what was and wasn’t done in the bible, and it is not scriptural to christen or baptize and infant…but it is scriptural to dedicate a child to the Lord just as Jesus was brought to the temple as a babe. Water Baptism in the Bible was only used as a public confession of repentance from sins and by those old enough to understand the meaning and make the decision on their own.

Think about the model Jesus set…dedicated as a child, water baptized as an adult.

Luke 2:22-27  And when the days of her purification according to the law of Moses were accomplished, they brought him to Jerusalem, to present him to the Lord; (As it is written in the law of the Lord, Every male that openeth the womb shall be called holy to the Lord;) And to offer a sacrifice according to that which is said in the law of the Lord, A pair of turtledoves, or two young pigeons. And, behold, there was a man in Jerusalem, whose name was Simeon; and the same man was just and devout, waiting for the consolation of Israel: and the Holy Ghost was upon him. And it was revealed unto him by the Holy Ghost, that he should not see death, before he had seen the Lord’s Christ. And he came by the Spirit into the temple: and when the parents brought in the child Jesus, to do for him after the custom of the law,

Mark 1:9-11  And it came to pass in those days, that Jesus came from Nazareth of Galilee, and was baptized of John in Jordan. And straightway coming up out of the water, he saw the heavens opened, and the Spirit like a dove descending upon him:  And there came a voice from heaven, saying, Thou art my beloved Son, in whom I am well pleased.

The really good news is if something does happen to a child (baptized or not) who is not old enough to know wrong from right they do immediately go to be with the Lord Jesus. We have scriptural proof even in the Old Testament of this when David’s son died and went to Heaven. This child was not baptized and in fact was conceived out of an adulterous relationship. It shows how much God loves children!

2 Samuel 12:22-23  And he said, While the child was yet alive, I fasted and wept: for I said, Who can tell whether GOD will be gracious to me, that the child may live? But now he is dead, wherefore should I fast? can I bring him back again? I shall go to him, but he shall not return to me.