Life, Death, and Doors in Heaven

For some reason the subject of death came up at our house the other night. Andrew felt the need to inform Collin that "when you die, you don't come back to life". To which Collin replied, "I know!"

Then I added, "but you can go to Heaven".

To which Collin replied, "but you can't come back, there's not 2 doors. There's only 1!"

What's the scripture..."wide is the path, but narrow is the door????"