Here's the thing, all.
Koko the gorilla can communicate with sign language, and Koko the gorilla routinely lies to the keepers to avoid getting into trouble.
For instance, they'll ask "Did you eat my apple?" and Koko will sign, "NO! the kitten ate it!"
And they'll sign, "The kitten dids not eat the apple. You did, didn'tyou?"
And after a while Koko will go , "Yes, I ate it. I'm sorry." and hug the keeper.
That means, while we can't tell with all animals, we at least know that gorillas can sin. If a gorilla tells a lie then it's in defiance of God's law, so it can't go to Heaven unless:
- God holds sinful animals to a different, unspoken standard than the standard to which he holds humans
- A gorilla Messiah comes and is sacrificed for the sins of gorillas...a "Jesus Gorilla" if you will
- Jesus' sacrifice applies to gorillas and the gorilla can hear the Gospel and accept Jesus as his personal Lord and Saviour and "go forth and sin no more"
In the third case, when he Bible admonishes us to spread the Gospel throughout the entire world, it would mean that missionaries should be reaching out at least to gorillas and dolphins.