What evidence would convince you? That is a serious question, because for those that have faith none is required, for those that do not none will suffice.
All knowledge is good, by virtue of being true. What aspects of Christianity have been dropped; because of political strife in ~350AD? What books have been re-written to manipulate politics in the years since they records were origionally written.
Isn’t having a touchstone - something that has remained UNCHANGED for 2,000 years a good thing? Many of the origional texts have been lost - and can never be replaced. Having a reference record, is a good thing.
Consider, just as a point of reference:
First addressed to Peter: Matt 16:19 I will give you the keys of the kingdom of heaven; whatever you bind on earth will be bound in heaven, and whatever you loose on earth will be loosed in heaven.”
and again in Mat 18:18 “I tell you the truth, whatever you bind on earth will be bound in heaven, and whatever you loose on earth will be loosed in heaven.
Bind what?
1 Corinithians 15:29 Else what shall they do which are baptized for the dead, if the dead rise not at all? why are they then baptized for the dead?
Baptizing the dead is pretty specifically dropped from the rest of the New Testament. Why? What else was censored by an unknown caretaker?
Questions do not indicate unbelief; they are questions of a believer who is intelligent enough to realize that the current record is incomplete.