Replying to Existentialist Question

So I haven't been able to make up my mind on some things, if anyone is able to help me out great, if not i'll figure it out sooner or later I just feel like I need a little direction if anyone has gotten this far themselves. I know it's a stretch looking for this on NS but I thought I'd give it a shot as it's been bothering me for a while.

Let's say everything's made up of particles. Different particles for different things. All these particles are touching each other as a result of airlike substances (gas and all that) so if you do anything (i.e. move) you'll affect the particles around you. However, since there are different types of particles in relation to different things (gas, skin, trees, anything) there must be some type of space in between to differentiate between each type of particle.

I think that we could either all be connected through these particles so that everything we do causes a reaction with another being OR our actions could fall between the cracks of everything so that what we do does not matter. So theoretically I could burn down a building and it will not effect me at all. Sure i'll be arrested and all that but it will have no effect on my being. It will have an effect on somebody else if they believe that it does. But if I believe that I am not connected to that person so therefore I will be able to go on living and will not care about it. I will not care about the issue morally because since we are not all connected it doesn't matter.

I would like to believe that we are all connected but I feel like if I do that I am putting my faith in something that I cannot see, which would make it plausible for me to believe in a higher being which I firmly do not.

How can I tell whether or not my actions are worthwhile when every person is destined to the same fate? Sway me in the direction of connections/a higher being or the belief that nothing we do matters and we all end up dead anyway so there is no point other than to satisfy my wants. Thanks for the help!