Technically to simply have faith in the absence of empirical proof is irrational.
That isn’t necessarily bad if it produces positive social and cultural outcomes. For those with faith, it’s also very real — there are many things that are irrational that people experience (e.g., phobias of small places, belief in the ‘triumph of human spirit’ in the face of adversity, etc.). And, in many ways it’s been necessary for human evolution and the evolution of society.
However, it is not rational. Rationality, by definition, focuses on verifiable information and making decisions based on that information. And let’s not point to the Bible (insert book of faith of choice) as ‘proof’ concrete because any serious religious scholar (including those who are members of the clergy) say that it’s foolish to take the Bible as empirical proof — that without understanding the larger social and cultural contexts, we cannot truly understand its lessons.
So, I think that most of us without faith are exasperated in our often had conversations with many modern American “Christians”. It’s exhausting to live in a religious society (i.e., the US) when you’re not a person ‘of faith’ because we have to defend rational reasoning and empirical proof of many thing (e.g., those who don’t ‘believe’ in climate change also tend to be those who believe in God and GOP politics). The US has become not just a religious nation, but a nation of anti-intellectuals who use pseudo-intellectual arguments as logical fallacies or just outright dismiss anything that threatens their world view.
That is not to say that people of faith can’t also be 99% rational in their lives, their interests, and their pursuits. For example, the Jesuits seem to fall into that camp. They still have faith, but reconcile their beliefs with interests in the pursuit of science, philosophy, empirical truths, and education as being the work of God. The work of God bit I could personally do without because I don’t need that to feel fulfilled in my life. Others do, but most Jesuits that I’ve had the opportunity to talk to, don’t dismiss people simply because their beliefs differ. In fact, an active part of the Jesuit mission and education is for everyone to question religions of all kinds.
We’d frankly have a lot better conversations if “Christians” in the US modeled themselves after the Jesuits in their pursuit of faith, science, philosophy, and education. Unfortunately, they don’t — instead Fundmentalist beliefs disproportionately influence American politics and thus American “values”.
So, you’ll have to forgive us non-believers… we’re sick of politics and life being hijacked by a loud-mouthed minority of irrational people who functionally want a theocracy that serves the interests of the wealthy, that rejects analytic thinking, and a repressive social existence.