What does an Open Source Evangelist mean

I got a recent tweet - What does open source Evangelist mean?

What does an evangelist mean?

Wikipedia has a definition for Evangelist and Evangelism

It says,

Evangelism is the practice of attempting to convert people to a religion.

For me, Open Source Evangelist would be about:

• Following a religion of Open Source.
• And, trying to convert few people from "non freedom" software to "Freedom Software".
  

More References:

[#] Linkedin had a question: What does Software Evangelist mean?

[#] Guy Kawaski also blogged on technology evangelists.

P.S.:

Free software is not about free, as in money. Its about freedom.

This also reminds me of a joke:

Would you park if the sign board reads: "FINE FOR PARKING"