My guess is they refuse to want to give God the glory for their faith because they have to give up on believing in their free will.
I don't see this conflict or choice. Plus it's seems a contradiction to choose to stop believing in free will.
The simple answer would be: "Faith comes from what is heard, and what is heard comes by the preaching of Christ." If this is what you're looking for you can stop here.
This answer is true of my ongoing development of faith, but, if you're still here, I'll bore you more 'musings' as our friend would put it. Because it's an interesting question for me to explore.
I'm not sure that I was born with a childlike diffused trust in something larger; I think so. I am sure that whatever faith I had was gone after many decades of pursuing more darkness than light.
At the bottom - I certainly hope it was the bottom - I had a conversion experience. I would say my faith - trust and confidence in God - began anew here. A direct conscious experience of God's presence and love. Without His grace then, I don't want to think where I would be now. Surrender, giving up figuring it out, also had a great deal to do with it.
Though it certainly waxes and wanes, this experience, or the memory of it, stays with me very strongly. It is nurtured most by prayer and the sacraments, the more constant these are, the greater my realization of God's presence, and the more real my faith becomes.
It's not that God comes and goes, but that I come and go in my remembrance and attention and focus on God. He is always present, but to know this, I have to be present to Him also.
This may not be the proper answer for all Catholics, excepting contemplatives perhaps. I know some Christians hold that it involves choosing to believe. Perhaps I am a hard case, but this only raises more questions for me; questions that fade away in prayer.
I know that the usual method is "hearing the preaching of Christ" first, then faith. For me it was backwards: initial faith experience, then God's leading me to the Church, hearing Christ's words as if for the first time, the sacraments, deepening faith, spriritual practice, prayer, faith, and so on.
Put another way, my faith comes from being with God. This is my personal answer, and not one that I'm saying is the case, or should be the case, for others.
Faith ebbs and flows but God promises He will never leave us. It's hard to say if you were seeking or if you had simply fallen away for a time. God works in mysterious ways. But you would never be where you are now if God had not given you the faith you have today. You know it and I know it.
Fact is, if we don't believe faith comes from God why would we believe His word came from Him.