I would count as tangible something that is measurable and repeatable under controlled conditions. I cannot understand why a benevolent god would be so cruel as to deny that, while requiring our belief, as a prerequisite to salvation.
What would this look like in your opinion? I gave the example of Eucharistic miracles.
Also, you’re presuming that empirical, scientific knowledge is the only reliable source of knowledge. What about reason? Or intuitive knowledge? You can probably know that someone loves you without scientifically measuring it under controlled conditions. It isn’t as if we believe in God without any sort of evidence whatsoever. We have texts and numerous people throughout history who attest to personal encounters with the divine, including some that speak about God as having revealed himself to us in the person of Jesus. The question isn’t whether we have evidence or not, it’s whether the evidence is convincing enough. It is only in the last hundred years or so that people have begun to see “science” and empirical, testable evidence as the only acceptable form of proof. That’s just bad philosophy.
Christians have believed since the beginning that if someone doesn’t know about or believe in the Christian God but is sincerely seeking the truth, that person will be saved. So God doesn’t necessarily require belief.
As far as process theology goes, that doesn’t sound too different from mainstream Christianity. I would say the main difference is that God could impose his will on us, and does provide us with some degree of empirical evidence in the form of Eucharistic miracles, incorruptible saints, the image of Our Lady of Guadalupe, etc., but that ultimately, in order to enter into a loving relationship with him, we have to have faith. If God is God, and he gave us empirical evidence directly demonstrating his existence, we would not have faith and would simply know in a more absolute sense that God will always keep his promises. But that’s not how human relationships work. Because we are not gods, we can fail to keep our promises, and every human relationship therefore requires trust and faith that the other person will not turn their backs on us. God wants us to have that same trust and faith, otherwise there will be a certain coercion involved in following him.