No, I disagree with this as you have written it. It would be correct if you wrote “impossible to know/ prove with absolute logic/ physical evidence.” It would also be correct if you were writing about our own assurance of salvation rather than the existence of God. However, it is NOT correct to claim that people can’t believe in God with absolute certainty, and that if they say they do, they lack humility.
Some people are blessed with very strong faith, and indeed it is a blessing that not everyone receives. Many of them who are so blessed are very humble people. Children, for example. I don’t think the sainted Marto children ever once doubted the existence of God or Jesus or any of it. They were very young and believed as children do, without any overthinking. They were also very humble - they were just poor, lowly, not very well educated children, not in the least proud or trying to impress anyone. God was part of their daily reality the same way their mom and dad were.
Some people on the other hand, including some saints, will go through periods of doubt or uncertainty and will have to rely on confidence and trust in God to get them through those dark times. But God doesn’t give everybody the same trials, so not everybody doubts.
If you are going to ask me, have I ever had a doubt about God’s existence in my life, the answer is Yes, because I have lived a long time, not just a few years as a young trusting child. Fortunately these doubts have been small, momentary, and few, and easily banished.
But if you are going to say to me that I can’t possibly know God exists with absolute certainty so I’m just going about my daily business with some type of “confidence” that he exists, then that’s incorrect. And if you’re then going to tell me that I’m somehow lacking humility for telling you what I truthfully know/ believe/ think about every time I pray the Adoro te Devote (which is not about confidence, it’s about truth) then you’re really way off base.