Whoa! Long post incoming.
So, technically speaking, from a Christian perspective...going to Equestria is actually possible.
Now, I know that's a lot to believe, but bear with me here. Working under the idea that God is real and keeps his promises, and that everything in the Bible is real and accurate, one must take a look at Mark 11:22-24 and Matthew 18:18-20.
TL;DR: These two passages say that if you ask for something, and don't doubt that God can make it happen, it will happen. So with this in mind, if you ask God (in prayer) to take you to live in Equestria, he will.
This would undoubtedly happen after death, whereas your soul would be taken to Equestria and given a pony body instead of a human body.
This is just my two cents on the subject, but I believe the logic is there, so long as the truth of the Bible holds up. Maybe this gives hope to anyone who's serious about the idea.
Here's a bit more info:
https://ebible.org/prayer/key5.htm