Conversation so far:
What were Shaw's first political activities?
He began attending meetings of the Social Democratic Federation (SDF).
Was he an active member?
CANNOTANSWER.
Is there any additional information about his time with the SDF?
Shaw doubted the ability of the SDF to harness the working classes into an effective radical movement and did not join it.
What did he get involved with next?
Fabian Society, Shaw went to the society's next advertised meeting, on 16 May 1884.
He became a member.
How did he involve himself in it?
He joined the society's executive committee.
What did he do as a member of the committee?
provided the society with its first manifesto.
is there information about the manifesto?
published as Fabian Tract No.
2.

Question: When did he come to believe in Marxism?
Self-contained rewrite: When did George Bernard Shaw come to believe in Marxism?