I was an Agnostic back in college. I felt that atheism was too strong a stand. I did not have any evidence to believe in God, but I could not rule it out either. Agnostic is just a fancy word that means - "I don't know if God exists, I don't think its possible to know".
The turning point when I became an atheist was when I came across this quote by Feynman,
"I call myself an atheist. Agnostic for me would be trying to weasel out and sound a little nicer than I am about this." - Richard Feynman
I realised how I was afraid to admit to myself what my true beliefs was. I aimed to be honest to myself and in pursuit of that I had to admit that you believe in things you had evidence for and you don't believe in things for which you don't have evidence. The lack of evidence is not due to a lack of looking. Also atheism never claims to never believe in god, ever. With new evidence at any point of time I am willing to update my beliefs.
So I decided not to weasel out and try to get along with everyone. I henceforth self identified as an atheist.
A relevant quote from Richard Dawkins is - "I am agnostic only to the extent that I am agnostic about fairies at the bottom of the garden."
In atheism I reject the existence of any deity - a supernatural being, which interacts with humans. The theories people usually offer for how these deities supposedly operate are not falsifiable. There is no empirical evidence (the repeatable kind) to support the claim that they exist.
The next time I seriously thought about this topic was when I was in that phase of binging Jordan Peterson's videos. I highly recommend his biblical series, which was where I was forced to consider alternative definitions for God.
His answers are hard to digest. I don't claim to understand what his idea of God is, but of his many attempts at explaining it, my favorite is
"God is the highest value in the hierarchy of values.” - JP
I think his view is that morality and religion are inextricably linked. The hume's gap is a real issue. For people like me all caught up in logic and science, I used to take the underlying values I operate on as implictly true. JP's "God" is the solution to this problem.
So now I guess the above is a better definition of God, something that easily lends itself to the "personal God" conceptualization. People holding similar value systems have similar Gods. God is an abstraction of all these values. Like how we have an ideal Man, Women, Father etc. Take it one level higher to get God. We all respect and admire God. We worship that God through our actions.
I'll come back and try to flesh out this better when I have more clarity. But this left me convinced that there is indeed a sense in which we can be spiritual without being religious.