A: Firstly, let us address the idea that babies WILL go to heaven after they die. I personally believe this and personally believe that God will judge accordingly and take into consideration that the babies did not have a chance to accept Christ. I believe there is a special measure of grace for such tragic situations.
For more reading on that topic, try this site.
Now, moving on to address if babies understand what is going on.
If we believe in Christ and we die, we have full assurance that we will go to heaven. And as we do, we are given new bodies as we lay to rest the ones that we currently have. We are not told how these "new bodies" will work or how they will look like, just that we are renewed.
Having said that, that doesn't mean that we'll forget everything. Isaiah 65:17 says this, "Behold, I will create new heavens and a new earth. The former things will not be remembered, nor will they come to mind." What this verse means is not that we will forget all things, but that we'll forget all things that no longer matter in heaven. The the things that have helped us worship God in heaven and enhance that experience, we will remember them. The things that hinder us from our authentic worship, those are the things that we'll forget.
For more information, please read this post by Pastor John Piper.
[answered by Pastor KJT]
