score:9
No intelligence is required.
The Bible assures us that even a fool won't go astray on the Way.
Isaiah 35:8 (ESV)
And a highway shall be there,
and it shall be called the Way of Holiness;
the unclean shall not pass over it.
It shall belong to those who walk on the way;
even if they are fools, they shall not go astray.
What is this Way, then?
John 14:6 (ESV)
Jesus said to him, "I am the way, and the truth, and the life. No one comes to the Father except through me.
So even a fool following Jesus will be saved.
Jesus also states that the kingdom of God belongs to those such as children. Now, children can be intelligent at times, but certainly this doesn't sound like there's an intelligence requirement.
Mark 10:14 (ESV)
But when Jesus saw it, he was indignant and said to them, "Let the children come to me; do not hinder them, for to such belongs the kingdom of God.
Upvote:-3
All who sin apart from the law will also perish apart from the law… ~ Romans 2:12.
He will punish those who do not know God… They will be punished with everlasting destruction… ~ 2 Thessalonians 1:8-9
Yes - There is a minimal level of intelligence required to get into Heaven because one must at least understand what it means to:
Ignorance of these three things would necessarily prevent entrance into Heaven because these are the very things that define a Christian. Without a rudimentary awareness of these concepts (even if not from the Bible) one may be rightfully labeled a "non-believer" (though not necessarily a disbeliever, because ignorance of the Truth doesn't necessarily imply a rejection of it).
EDIT: In response to a comment, I'd like to add that the above does not apply to a baby who dies before Baptism. While I can't speak to every denomination, I know that the Catholic Church has changed it's position several times on this matter, but the current teaching holds that:
"...Infants who die without baptism are entrusted by the Church to the mercy of God..."
EDIT 2: Indeed, I am drawing an important distinction between someone who perished before they had a chance to experience God (or someone who was mentally incapacitated) and someone who either carelessly or willfully remained ignorant of God throughout their entire full life.