The idea of the "spirit world" brought Houdini and Doyle together through attempts to contact Houdini's mother. However, this same idea separated them when Houdini spoke publicly that he did not believe in spiritualism.
We can arrive at this answer because:
Houdini knew the spirit section was a hoax, but he said nothing in the name of friendship with Doyle. This brought the two together, as Doyle believed Houdini shared his faith.
However, Doyle began to introduce Houdini as someone who had great faith in spiritism. Houdini didn't like it and said publicly that it wasn't true and that spiritualism was a big hoax.
This cooled their friendship and caused them to drift apart.
More information:
https://brainly.com/question/1129013?referrer=searchResults