The answer here is simple. Celtic pagans have a different tradition and believe in different Gods and Goddesses and a different afterlife. Egyptian Gods include Set, God of death, Anubis God of life, and Isis. I am not sure of any specific Celtic Gods except that in the neo tradition there are a male and female deity who are married. Entry into paradise is different between the two Egyptians weigh the heart to judge your character and entry in Celtic paganism is based on pleasing the Gods, I am not 100 percent sure of the latter however.