Tricky - one has to avoid anything in which intellectual shenanigans has much of an effect: anything in which conclusions are sensitive to abstract reasoning or degree of knowledge.
This renders hazardous a dependence on the interpretation of scripture except when this is plain and undeniable (and what is plain and undeniable to a Clever Silly is evidently not much).
And clearly the modern institutional church is itself substantially dominated by Clever Sillies - so the acceptance of church authority is a matter of out of the frying pan into the fire.
So we are left with tradition - the consensus of devout Christians through the ages (through the past 2000 years, and not neglecting the first 1000 years).
I think tradition is the best that can be done.
Of course this means that a modern Christian must either reject or regard as insecure all recent (past few hundred years) innovations and additions - but that's okay.
For a clearer understanding of Clever Sillies see: