Starting the Mission(s)
Once you've completed the story mission Father and Son, Michael will able to access the Epsilon Program website. Pull up your phone's internet app or sit down at any computer to log in. Search "Epsilon" in EyeFind and click on the first link, then fill out the evaluation form. Your answers have no bearing on the side missions.
After the evaluation, Michael will be asked to find a certain red truck...
Seeking the Truth
A question mark will appear in Raton Canyon. Head there to find the red truck in question. This side quest is nothing more than a cutscene, so head to the truck and get it over with.
You'll then receiving an email asking for a $500 dollar donation to the Church of Epsilon. Head to the website again and pay the money, or the next mission will not appear.
Accepting the Truth
The next mission will open up shortly; look for the Epsilon logo on your map. When it appears, head there to start the next leg of the enlightenment quest.
This time, your new contact Marnie will ask you to purchase further enlightenment for $5,000. You know what this means. Head to the Epsilon website once again and make a $5,000 donation.