In pretty much every field that we begin to learn, we do not question the end.
Take biology. Even today, we don’t understand it fully. And yet, we have biologists and zoologists and all types of medical professionals, who never questioned whether biology exists, but simply began working towards their goal, studying and researching day after day.
Ditto for physics and chemistry and every other field out there.
When changes occur in the understanding, then the learning process is quickly re-adapted.
But in spirituality alone, most non-believers first want to establish the presence of God (ie the end point) and understand Him in entirety. Just as any saint or realized soul would tell us, God is unknowable and unfathomable to the human mind and intellect.
So what’s the way out? Simply going back to the basics, and living a spiritual life, in service of others, not day by day, but second by second.