Nowhere in Scripture is judgment ever rendered without accountability. The Bible puts hearing before believing: “Most assuredly, I say to you, he who hears My word and believes in Him who sent Me has everlasting life, and shall not come into judgment, but has passed from death into life” (John 5:24).
I believe that children who die in infancy, children who die before they can know right from wrong, and those with mental issues which prevent them from understanding the gospel go to heaven. In order to be held accountable, a person must be able to understand that he is a sinner deserving of separation from God, Jesus Christ died in his place, and rose again on the third day. We are His only through simple trust in Christ alone to save us. In other words, a person must be able to understand the simple truth of John 3:16: “For God so loved the world that He gave His only begotten Son, that whoever believes in Him should not perish but have everlasting life.”
That leads us to the following question: What is that age of accountability?
Nowhere does the Bible give a specific, universal age when a person is accountable. People mature at different ages and at different speeds, so they understand the gospel at different points in life. I have met children who clearly understood when they were five-years-old and others who were not able to understand it until they were much older. I believe in the importance of leading children, not driving them. One dare not approach children with the idea that if Johnny understood the gospel at five years old, then so can Susie. It is important for a person to make a sincere decision about the gospel rather than a forced, false one.
The bottom line is that there is an age of accountability, but that age differs with different people.