There is some confusion in the question. Atheism is the lack of belief in god/s, not a belief there are no god/s. This is important because it involves how the burden of proof works.
Example from Matt Dilahunty: Someone is on trial for a crime. Now that person is either guilty or innocent of that crime. However, we do not determine innocence in a court of law, we only determine guilty or not guilty. Now lets say when confronted with the evidence, I don't believe that the defendant is guilty, and therefore find them not guilty. That doesn't mean I think that they are innocent. They haven't been proven guilty or innocent, but based on what I have available I don't believe they are guilty, we haven't even examined whether or not they are innocent.
This is the same for the statement "God/s Exists." Atheists are saying, when confronted with the evidence, that we find that God/s are "not guilty" of existing. Simply we don't believe they exist. What we are not saying is that we believe in fact they cannot exist.
This is important because your question "what makes you believe no deity exists?" is not accurate. Atheists DON'T BELIEVE claims that they do exist. We are not claiming that they do not exist. However, if I were to say I BELIEVE god/s don't exist, I'd be making a claim that I would have to support.
Why this is important is because nobody can prove unicorns, dragons, flying spaghetti monsters, pixies, magic, and so on don't exist. All we can say is that there is no evidence that any of these things do exist and therefore I don't believe they exist.
Same for god/s, there is no good evidence, therefore I don't believe they exist.
So, I know some people like to call themselves agnostic because atheist has negative connotations with it and has been used a a slur. However, it doesn't tell you anything about a persons beliefs. Theism is the belief in god/s. Atheism is disbelief in god/s. Gnosticism is a claim of knowledge something. Agnosticism is a claim of not having knowledge of something.
I personally don't care what you want to call yourself, but there is a difference between having a belief and claiming knowledge. There are people that believe in god/s who claim to know it for a fact, and others who believe and claim not to know for a fact. Just like their are those who don't believe who claim to know for a fact, and those who claim not to know for a fact.
Gnostic Theists and Atheist, those who claim to know one way or the other, have to prove how they know. Agnostic Theists and Atheists, those who claim not to know one way or the other, don't have to prove anything.
I will say this though, claims of existence are by there very nature unfalsifiable. They can potentially be proven, but can never be disproven. Therefore, I say that the atheist position of disbelief until proven is the only logical position.

I call myself an agnostic atheist. I'm absolutely certain that none of the gods I've ever heard of exist, because there's no proof for them and science contradicts claims about them. I can't rule out the possibility that some other deity exists, but I think it's wildly improbable. Therefore I'm technically an agnostic, but I'm an atheist in practice.

The existence of god is a supposition or an hypothesis. And an hypothesis without a backing evidence should be rejected, especially when there is an alternative hypothesis with reliable evidences.

When I got my necktie caught in A typewriter. ---Woody Allen

Atheism is as much an anti-belief as it is a belief ie; regardless of hardship I refuse to believe in the wizard in the sky. Same as Christian or Agnostic belief requiring that regardles of situation God has fortold it. It all comes down to if you believe in wizards in the sky or in your own ability.

I like to say that I have exactly as much confidence that there is no god as I do that fairies don't exist. Could I defend the position that I absolutely know gods don't exist? No. But there is zero evidence of the supernatural, and the evidence we would expect to find is missing too. I am therefore reasonably confident that there is no god.

For the same reason you are an agnostic, I am an atheist. I firmly believe that if gods did exist, they would have left their signature everywhere.

Religious theologians actually teach a false narrative about Atheism and Agnosticism. Your opening statement tells me you are still laboring under that.

" I think atheism is based more on belief rather then empirical evidence and science, though much evidence would concur that there isn't a God.."

This tells me you are viewing Agnosticism and Atheism as points on a linear line, on the left, Theism, In the middle Agnosticism, and on the right Atheism, this is FALSE and INTENTIONAL by theologians.

A-Theism is a response to Theism, the a prefix denotes "lack of"
This is a position on belief, you have a belief in a God, or you lack a belief in God

A-Gnosticism is a response to Gnosticism, the A-prefix denotes lack of
This is a position on Knowledge, you claim to have knowledge of a God, or you claim to lack such knowledge of a God

Religion does not want to even acknowledge Gnosticism, because by doing so they have to admit Atheism (a lack of belief) has weight.

With the FALSE linear model, they teach followers that Atheists are COUNTERCLAIMING, claiming that Theists claim there is a God, Agnostics do not know, and Atheists claim there is no God. That is wrong both on linguistics and basic honesty.

The lack of (good) evidence. The best arguments only prove that someting happened and now we have a universe. It says nothing about that thing's attributes or even if it's a being or a natural event. The clasical arguments say nothing about that thing sending its son to die and free us from our sins. on Calvary. So, until I have better evidence, I'll assume that we human beings are a product of natural events.

Lack of evidence certainly. You certainly can't prove a negative. Like in a Court of Law we either conclude Guilty based on Evidence, or Not guilty because of lack of evidence/ reasonable doubt. We don't have to prove innocence, nor should we.

You’re right that non-existence cannot be proven. Most atheists don’t say that we’re sure there isn’t a god. We choose not to accept the available evidence and don’t live our lives based on a religion. We also tend to not believe in Sasquatch or the tooth fairy, but we’re less well known for that.

There is no proof and until there is, it is totally silly and the biggest and most successful scam ever visited upon man.

What makes you believe Harry Potter doesn't exist?
Or Unicorns?
Ooh I like unicorns.

Somehow this tends to get conflated when the subject is God. If you put it in perspective though, I don't believe in fairies or unicorns either. Could they exist? I suppose. But so far I have no reason to even entertain their existence. Likewise, I haven't seen a single shred of anything I'd consider evidence for God's existence. Thus, I don't need to be conflicted about whether or not there's some possibility such a being might exist or something.

There is no proof for the existence of god and the whole concept is silly.

It's not logical to believe in a god. There is no evidence that a god exists. And on top of all of that, you can claim anything is real if the only basis of believing in it is that nobody has proved it doesn't exist.

Throughout history humans have always created a god to explain that which we don't understand, why there is thunder, lightening, how the rain falls and river flows. Slowly through science we have explained away many gods, now we can go back almost 13.7billion years scientifically, and yet because we don't yet know what happened before that we again cling to the habits of our ancestors and claim that there must have been something. To me that is closing the door on the possibility of so much more discovery. There is absolutely no evidence that consciousness can exist without a physically mind. If something can't come from nothing it still doesn't explain where god came from. Athiesm to me is the default position. I don't sit here and say "hmm well there could possibly be unicorns so I'll just take the position of not knowing" I say "there is no evidence at this time supporting the existence of unicorns, so I don't think they exist". Athiesm is the same. There is no good evidence that a god exists therefore I don't "believe" he does. I'm rejecting the claim until it can be proven to me.

The burden of proof is not upon the non-believer, it is on the believer themselves. No one has to prove there isn't one simply to make the case that a god doesn't exist. Just like in court, the burden of proof is upon the accuser, not the accused. If they want to make the case for a god's existence, that's on them, and not on anyone else to prove that there isn't one.

Though it’s true that one can not prove a negative, it must be said that atheism is not a belief system, it’s a conclusion. Since there is nothing logical or reasonable about any of the 3 major monotheistic belief systems, and certainly no evidence to support their claims, it is merely a logical, reasonable conclusion to make that there is no deity.

I was introduced to deities later on in my life. I guess if you're not indoctrinated from a young age it's easy to just accept life as it is without trying to think a deity is responsible for your shortcomings but even more infuriating for your skills to be considered gifts. For me at least I never needed a god. I've wished one would exist to stop massacres but the fact that they weren't stopped reinforced my gut knowledge that there isn't anything up there

This is an ill-formed question. It incorrectly places the burden of proof on the "atheist" to explain why ". . . no deity exists?" To quote the great Christopher Hitchens, "That which can be asserted without evidence, can be dismissed without evidence." With no credible (testable) evidence to support a positive deity assertion, there is no reason to accept this claim
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Atheism is not believing no god exists, it's the lack of belief in any god.

There is no God let alone a supernatural version of the animal that is a homo sapien sapien.

As of now, there is no empirical evidence of any gods existence, Theists have had thousands of years to offer evidence, they have not been able to do it.

Until they come of with evidence, I will have to say that there are no deities .

I do not feel the need to explain a non-belief. It would be like arguing a double negative.