Once one admits that God's existence is undecidable, s/he can either live in fear of both possibilities or live free of both possibilities. Having no use for unfounded fear, I personally much prefer the latter option. God, if it exists, is irrelevant. Any spiritual activity I perform is for my own benefit and for the good of those around me, never for the consideration of a possible being that couldn't be bothered to manifest itself and make clear what its moral rules (if it has any) actually are.

It could be argued by the religious that in some cases they did manifest(according to their beliefs), and there's actually an excess of copies of the rules if considering the amounts of the Quran or Bible printed.