If this mystery hasn't been being tried to be kept secret since the Gods left the planet, it will have been revealed by now.
Is the usage of the Present Perfect Progressive Passive and the Future Perfect Passive possible here?
Of most concern to me about the sentence is the opening clause. Use of 'this mystery' as the subject in the passive voice really does not work.
You need to say something like If attempts had not been made, since the Gods left the planet, to keep this mystery secret....
And since this is an 'if' clause you need to use the conditional in the main clause - it would have been revealed by now.