I will defend 3 basic contentions; I will then apply them to the question in the OP.
- All belief is based on evidence
- All evidence is at its core experiential
- Faith is not passive belief
1. All belief is based on evidence
Sometimes people looking for a fight will say “there’s no evidence for God” or something similarly provocative. When carefully investigated, the claim is found to be a word game. This statement is achieved by defining evidence to mean something different from its customary use. For example, one might define evidence as “absolute, unimpeachable, empirical proof.” The trouble with this definition is that it would mean we have no evidence for anything. No human discovery of science, philosophy, or theology meets that burden of proof.
The reason science cannot meet this challenge is that science doesn’t prove things, it disproves things. It’s a remarkably effective method for minimizing type 2 errors. Of course, that comes at a cost—it means committing a lot of type 1 errors. You are grateful for those type 1 errors every time you board an airplane.
On the other hand, if we define evidence in a way that accords with the ordinary use of the word, something like “an observation that lends credibility to a hypothesis”, now we have a definition that matches actual human experience and behavior.
Humans believe things because they have discovered or been given reasons (i.e. evidence) to do so. Whether or not those reasons are valid is beside the point I’m making here—the point is there are reasons.
2. All evidence is at its core experiential
Some will assert that experiential evidence doesn’t count. The trouble is, this too will rule out all evidence, because all evidence of any form rests upon a foundation of experiential evidence. Whether that evidence came from an equation, a machine, or human senses, take it back a few steps and you’ll end up with a human mind. A human mind developed the mathematical axioms and the machine, and a human mind interpreted information presented by the senses.
Experiential evidence can be aggregated for statistical significance, filtered to remove errors, controlled to exclude outliers, etc., but it still passes through the experience of the human mind.
Whether or not those experiences are appropriately interpreted is beside the point I’m making here—the point is we believe things because of experiences.
3. Faith is not passive belief
Thou believest that there is one God; thou doest well: the devils also
believe, and tremble. (James 2:19)
Clearly something more is expected of the faithful. The word itself connotes action, because sincere belief leads to action. We act in accordance with what we believe, whether that belief is that pressing the brakes on a car will prevent an accident, or believing that refraining from sin will produce a better result than the alternative.
Faith is sometimes defined as “belief without evidence.” Not only has this been addressed in the first section of this post, but it is also a non-Biblical definition. The English theological word faith relies upon the Greek “pistis” (conveying trust) and the Hebrew “aman” (conveying certainty).
Faith is exercised when we say “this person/book/process/source/etc. worked for me last time, so I will trust it enough to use it again." Thus trust implies belief sufficient to justify action.
Whether or not that trust is well-placed is beside the point I’m making here—the point is we act because we trust.
To those who say you cannot believe in things you do not see, I would ask, do you believe in protons?
To those who say it is foolish to believe the testimony of another, I would ask, do you believe in the Big Bang, and if so, have you personally validated the Einstein Field Equations? If not, you are trusting the testimony of someone else.
Since none of us are experts in everything, we have a system of degrees, accreditations, credentials, and references to help people figure out who is reliable. It's a system that produces a lot of good results, so we exercise a lot of faith in it. But that's important--all of us rely on things in one or more discipline of science because we trust the people or the results, not because we understand all of the details. That's what faith is. Curiousdanni has thoughtfully described faith as "Relying on something because of its past behaviour".
Those of us who believe in science believe in things we do not fully understand, and we do it all the time, on the basis of faith. And we're rational to do it!
For those who find this unsettling and would like a more extended discussion, I go into further detail regarding the interaction between faith and science in this video.
My understanding of the passage in the OP is that Jesus is not scolding evidence-based belief (that would be all belief), but pointing out that where sufficient evidence has been given He expects people to accept it and act on it.
Thomas had been given reason to believe—he had felt the power of Jesus’ teachings, witnessed miracles, listened to the predictions of Jesus’ death & resurrection, received the promise of the Holy Ghost, and heard the testimony of trusted peers that Jesus had risen. Apparently God expects many people to believe—sufficiently to act—with less evidence than this.
Blessed are those who have not seen and yet have believed (John 20:29)
My message and my preaching were not with wise and persuasive words,
but with a demonstration of the Spirit’s power, so that your faith
might not rest on human wisdom, but on God’s power (1 Cor. 2:4-5)
If any man will do his will, he shall know of the doctrine, whether it
be of God, or whether I speak of myself. (John 7:17)
Indicate that God expects to provide reasons to believe, expects people to test His promises, and expects them to act rationally based upon that evidence. To demand more evidence ad infinitum is contrary to the purposes of God and is irrational.
My own experience with this process is described here.
We never make life decisions with all the evidence; we evaluate some of the evidence and eventually make a decision to trust, or not to trust.
God wants us to learn to trust, and specifically to learn to trust in His Beloved Son, Jesus Christ. If He gave us literally all the information He has it would both blow our minds and destroy the exercise of learning to trust.
Is believing based on evidence good or bad?
- It is good to believe based on evidence. It is good to put God’s
promises to the test.
- It is bad to tell God we don’t like the evidence He’s given us.
Ask, and it shall be given you; seek, and ye shall find; knock, and it
shall be opened unto you: (Matthew 7:7)
I conclude that it’s okay to ask for more evidence, provided we are also willing to act on the evidence we already have.
Richard Scott, a man who was not only a nuclear engineer, but also one of the great theologians of the last century, gave a discourse about truth, and how it is accessed through scientific and theological methods--see here