Since you have shown a genuine desire to understand the atheist, I would like to share with you my personal stance. Understand that it is my thinking and any resemblance to other atheists on this forum is purely coincidental.
When it comes to faith, I don't have even a mustard seed's worth. I just don't have any. Nada, zip, zero. Nope, none. No faith here. Sorry, fresh out. I used to have faith. I had a whole passel of it along with magic and superstition. I had faith, and myth and magic and superstition, and superdupernatural, super Jesus juice.
When I was very young, I used to have a pillow. A very special pillow. One that I used to cover my face. I covered my face so you couldn't see me sucking my thumb. No one ever knew.
At night, when scared (as everyone knows) when you close your eyes real tight and hold your breath for a count of ten...instant invisibility! It is impossible for the booger man to see you when you do this. And I am living proof that this works.
If you pick up a piece of food within 3 counts of dropping it, no germs. Gauranteed safe to eat. Because I'm quick, I have never been sickened by eating food that I have dropped.
Throwing a dash of salt over your left shoulder gives you good luck, but walking under a ladder guarantees you bad luck.
Be a good Christian. When you die, you'll go to heaven, get an incorruptible body and walk on streets paved with gold.
What's the harm in believing these things, if it helps me live a happier life?
Because they are not true! They are stories to help us cope with the harshness of reality. A way of dealing with life's hard, sharp edges. They are tricks used to manipulate and control behavior. They are myths used to explain things we do not understand, and to make us feel safe. They are lies and a lot of fluff to fill the gaps in our knowledge. Why believe in fairy tails? Anything believed that is not true, devaluates the truth.
There was a time in the past when magic and supernatural forces filled in the gaps in our knowledge. The gap, what we don't know, has shrunken considerably since the days of dragons and things falling off the edge of the earth.
What experience has shown us, is that there are natural explanations for everything, but there is no empirical evidence what-so-ever, for anything supernatural.
A little logic and reason and critical thought and...scientific investigation...and one by one the old false beliefs have fallen away to be replaced with facts and reason and evidence for why things are the way they really are.
We were small and gullible once, but we quickly learned that there is no tooth fairy. We figured out all too soon (or knew all along) that Easter bunnies don't lay chocolate eggs and Santa Clause doesn't deliver presents on Christmas. But what we failed to learn, was that it is no longer necessary to make believe, once we are able to observe and reason and understand.
Kissing an owie, that really does help, but no, there is no pot of gold at the end of the rainbow, and I’ll bet there are no golden streets to walk on in heaven, There is no evidence for an afterlife. God does’nt throw lightning bolts and seizures are not caused by demons. There are no talking snakes or donkeys and zombies don't come out of the grave. The sun never stood still and the earth was never covered in 5 miles of water. There is no heaven, or hell, or God, or devil, or angels, or demons.
Life is what we make of it, not what we make up about it. And why make believe when the truth is so amazing to begin with?
Now, pull up your big boy pants, roll up your sleeves and get to work at finding out what reality is all about. When you don't know, say you don't know, but never make stuff up. And don't let others make up stuff for you either. You don't need to, there is plenty of stuff to think about without make-believe.