Spiritual truths are spiritually discerned and the man without the Spirit cannot understand them.
When we were Catholics, and spiritually dead, we were clueless about spiritual issues, because, as you say, we didn't have the Holy Spirit enlightening our minds.
One of the things that stood out to me, after becoming a true Christian, instead of a pseudo Christian, was the incredible spiritual blindness I had.
Hey MHG, time to shake the dust off your feet?
:-)