No one has said that disagreeing per se is negative. But, to dismiss without acknowledging that there are other ways, that other ways are as good, or maybe better, is to denigrate others points of view and feelings, which definitely is a negative approach.
It's closed minded because you are insistent that your way is the right way. You are not willing, or perhaps able, to consider that you might not be right. You state that not everything can be explained, which is of course a valid viewpoint. But then take the leap that that means it can't be questioned. Its the sort of sleight of hand that confidence tricksters use, and frankly debases the debate.
I have not seen atheists mocking; they have asked questions that you do not answer, other than in riddles, which get questioned further. If you interpret that as mocking then that's on you
And, to your final paragraph, it's pefectly possible to ponder one's existence without needing religion in your life.
I have spent many months and years pondering the meaning of life since my husband died. I'm at peace with the reality, which is that we are born, we live and we die. I am lucky to live when I do, in the place that I do, with the people that I do and to have experinced the things that I have. Belief in something else has never been needed. Along the way we we support and nurture family and friends, we do good things and we have lots of wonderful and some not so wonderful experiences. We are curious, we learn, we travel, we explore. We try to have a positive impact on those around us. All without feeling the need to attribute this to some nebulous higher being.
You might take a different approach That's also fine :)