How can we know if something is true? It works. It is operationally effective. That is the surest test of what is true or not. If it works for some and not for others, then what? Well, the truth apparently varies from one to the next, if that is the case.
Fundamentalist religions, the kind which have a sacred text, have much different definition of truth. For them, truth is revealed verbally and is inarguable and fixed for every last person. Truth
One needn't ponder long to see the vast difference between a truth that can be tested operationally and thereby verified and religion's contention that truth can only be known by rightly interpreting a written document. The former can be embraced rationally and demonstrated as true. The latter is a total leap of faith, an arbitrary decision to believe a "truth", the validity of which is merely assumed. Truth of this latter type is accepted largely because of tradition, convenience, peer pressure, and personal advantage of some sort.
Now, if one were in the sincere business of teaching people to embrace a truth for their personal benefit, what would be most effective, demonstrable truth or asserted and unquestionable truth?
Jesus said he was the truth. That suggests that what he taught was truth. Does the truth, which Jesus represented, work? Can its validity be verified?
The church's contention is that the truth of Jesus gets you out of a bind with God. You'll only know for sure that it worked after you die. In this life, all you can do is hope. Faith is said to be necessary, faith that God will honor his promise and faith that what the church has taught as truth really is true.
Realistically, the truth of Jesus can only be tested if we know what effect that truth should generate. As noted, the church's afterlife benefit is unverifiable. However, Jesus promised much for those who embrace his truth, blessings like peace, joy, freedom, abundant living. These are things that can be observed and enjoyed here and now.
So, why don't we test the truth of Jesus against these promised results? Can I follow the instructions of Jesus and enjoy all the blessings he promised? Conversely, can I embrace the truth taught by the church and see the same results? If so, maybe both truths are the same. If not, I have to wonder why.
Does the church actually believe that what Jesus taught was true? Or do they think his counter intuitive truth is unworkable and refuse to even test it? The focus on untested and untestable truth leaves those attached to the church in spiritual limbo, waiting and hoping, hoping and waiting for God's final verdict which resolves after the fact whether church truth worked.