I disagree, the belief system as described is strictly irrational, in the sense that its fundamental assumptions contain a inconsistency that then permits one to prove anything. (I.e. A = not A therefore anything.)
It's a case of a mind trained into a kind of cul-de-sac with no way out. For some people this keeps them on the straight and narrow, for others it runs them smack into a wall. But it is certainly irrational to believe in a Divine Omnipotent Creator who plays crude tricks on you.
Well, rumcajz points out Bertrand Russell's objection, and apocalypstyx presents a fascinating aspect of the matter too, but the problem I'm talking about is the nature of implication/causation itself.
Rationality rests on implication.[1] The system we're talking about literally has "GOD -> anything" as an axiom, so it's useless for reasoning. If GOD -> (A -> B) for all A, B, and "->" then you can literally "prove" that anything implies anything else, or that everything implies God, but you can't disprove anything at all. Saying that there's a part of the system that can change anything about the system is essentially saying that there's no system at all. "Black is white and you get run over at the next zebra crossing."
If you believe that God will play tricks on you then you have nothing external to rely on. Again, this can be good or bad for a given person depending on their context. It's useless for reasoning, but you don't actually have to e.g. believe in Dinosaurs to reach God, so in that sense having no ability to rationalize can be a benefit if it prevents spiritual doubts. But many people instead are simply trapped in impoverished world-models. To wit: the Universe as revealed by scientific investigation redounds to the Glory of God far more than, say, the concepts of "young-earthers", or people who believe God a trickster.
[1] This is actually the one article of faith at the foundation of reason and rationality: that the Universe is comprehensible in terms of causation. The OP's father's god-image is jealous of even this wane and paltry rival.
> the system we're talking about has purpose as an axiom and God as a (perfectly rational) conclusion.
I'm sorry, but I don't see that.
The quote was:
> "God is so powerful that he can do anything including placing all that evidence there to test our faith"
To me, that reads as "God, therefore anything". Specifically all evidence of X is evidence of God, even (and especially) if X contradicts God.
I don't see that it says, "Purpose, therefore God."
For what it's worth, responding to a sidereal comment of yours, I agree with you that "teleology, i.e. the assumption that existence has purpose, is not irrational".
> I don't see that it says, "Purpose, therefore God."
It doesn't. I'm extrapolating. I'm saying that it is possible that such a conclusion can be arrived at rationally, for example, but starting from teleology as an assumption. Because this is possible, you cannot rationally conclude that a person is irrational just because they believe in God. They might be irrational, but they might not. To settle the question you'd need additional data.
> it is possible that such a conclusion [God exists] can be arrived at rationally ... starting from teleology [purposeful Universe] as an assumption.
I agree and indeed I did something like that: I built a model of God based on the assumptions that feedback exists and time is eventually transcended by humans or other sentients through technology or other means. I eventually discarded that model, but it was arrived at rationally.
> Because this is possible, you cannot rationally conclude that a person is irrational just because they believe in God.
I agree[1], however, I didn't do that. OP's father isn't irrational because he believes in God, he is irrational because he thinks God makes fake fossils. It's a concept of God so foolish as to disprove itself. If it were possible to mock God this would surely be the way to do it. The Flying Spaghetti Monster has more dignity.
[1] I am rational and I believe in God, so it would be hypocritical of me to claim that a person is irrational just because they believe in God.
> he is irrational because he thinks God makes fake fossils
You can't know that without knowing how he arrived at that conclusion. You cannot judge the rationality or irrationality of conclusion simply by looking at the conclusion. When you do so, you are making the exact same mistake that atheists make when they look at you and decide that you must be irrational simply because you believe in Satya Sai Baba.
Sorry, I was using that as a kind of short-hand and obscured my meaning. That particular belief is a symptom of the underlying irrationality of his belief-structure but not in itself necessarily arrived at irrationally in the general case, eh?
> You can't know that without knowing how he arrived at that conclusion.
In this case we do know how he arrived at that conclusion and we know that it was due to a form of reasoning that obviates itself, that his reasoning is irrational, that he is, in fact, not reasoning by his own admission.
I can't say whether or not this religion is working for OP's father, but I can (and do) say that it is irrational, because it is irrational in its structure. Anyway, he doesn't have to reason correctly because (his) God(-image) does not require it, He is content with irrational faith.
Numbers are irrational. We can simply write 2+2 = 1 if we assume 1 is called 2. So how can you make religion irrational? Just because the story telling is bizzares and perhaps even unproven, doesn't mean the stories are irrational. We have science theories which cannot be proven and yet continue to be listed in the literature and called science. Let's respect religion. People have their preference and it is irrational and condensing to say we hold irrational beliefs. That's very insulting. I ask for apology here.
I began my conscious adulthood agnostic and irreligious. I sincerely and persistently pursued truth throughout my life, and eventually I found God. Sai Baba. I actually literally believe that Satya Sai Baba was/is/will-be an Avatar: God in Human form.
One of the many aspects of Baba's instruction is that one who loves God should rejoice when passing by any house of worship, be it a Church, Mosque, Synagogue, Temple, or an altar of unhewn stone. God is One.
Please do not think that I disrespect religion, and I apologize for giving that impression.
Anything that helps one cross the ocean of illusion and reach the safe shore of Eternity is good.
If a belief system helps you reach God then it is good even if it's irrational.
It's a case of a mind trained into a kind of cul-de-sac with no way out. For some people this keeps them on the straight and narrow, for others it runs them smack into a wall. But it is certainly irrational to believe in a Divine Omnipotent Creator who plays crude tricks on you.