Is guessing a way to God? If I 'guess' that there is a God and live accordingly, could I be considered a true believer? Can faith only be revealed? Is believing not a form of guessing?
No, you are not a true believer.  If you are saying that "living accordingly", as in mouthing prayers, attending church services, and living a basically decent life, while not actually believing that Jesus died for your sins, then no, you are not saved. 
Evidence: John 3:16 and Rom 10:9. 

Yes, it is a way to God. If you are saying that going through the motions is a way to God, then yes.  Evidence: 

1) "Faith comes by hearing" Rom 10:17. 

2) Dietrich Bonhoeffer in
    Cost of Discipleship offers the advice of "He who obeys believes,
    and he who believes obeys." He then goes on to advise "obedience" as
    a remedy to weak faith 

3) There's a folk tale of a Scottish pastor
    who started out as a charlatan. A nonbeliever, he wandered into a
    town and applied for a job as pastor.  The story goes that one day
    he broke down in tears while preaching, because he had converted
    himself.  One version of a similar story is here:
    http://stevenjcamp.blogspot.com/2007/07/george-whitefield-portrait-of-revival.html