FIRST
If you make a claim that something is or is not true or even that there is no way to know you take on a duty. It becomes your job to support it with arguments and evidence. And discuss and deal with arguments and evidence against you. The bigger the claim the more work you have to do. This is called the burden of proof.
Proof is not 100% proof but the making of a strong case.
The burden, for example, applies in religion to those who say God exists and also those who say that it is true that God does not exist.
Believers claim there is a God and sometimes try to argue that it is not up to them to show they are right or probably right but up to the critic or unbeliever to show they are wrong. They try to shift the burden of proof. If they could do that, that is no excuse for them not helping the critic with the research.
The fact remains that they are making the claim that there is a God. The burden is theirs.
If the critic or unbeliever tells them they are wrong then they take on the burden of proof. There are two sides then that have to assemble the evidence for their respective positions.
THE BURDENS...
We have some stunningly big claims to look at. Solid proof for them would be ideal from now on - but proof as in getting beyond reasonable doubt would seem to do.
Too often, claiming there is a God is considered to be delivering a burden of proof. That is a trick to hide how problematic the concept is. It looks better when it is over-simplified. To be exact, God is not about a burden of proof but a burdens of proof.
Burdens of proof if you claim there is a God are:
I need to prove that spirit – that which is there but is made of no parts is possible
I need to prove that spirit is real.
God is spirit. Proving that spirit is real is not the same as proving God - but proof is necessary for spirit. Spirits may exist without there being a God. But if spirits cannot exist neither can God for he is supposedly spirit.
Spirit is hard to grasp and many try to do it by contrasting it with matter and energy. So to claim spirit is real is also to claim that they are real. If you claim the right to prove matter and energy are real, then you lay claim to the duty to prove that spirit is real too.
What kind of spirit is another and separate question totally.
If spirit is a fact then I need to prove that this means there is a God.
I need to prove God is love.
I need to know he know he is alive.
I need to prove he wants a relationship with me.
At this point we have several burdens of proof. Religion has a heavy burden. Religion is dishonest when it sums up all these questions as God as if all you need to prove is God. It is not simple for God is a sum of many questions. There are far more questions than what we have listed.
Take the problem of evil. Each bit of suffering is so abhorrent and vile that even if we show evil fits God we have to try to make every INDIVIDUAL case fit too. This is only out of respect for the person and because if you can justify the suffering of 99 people that does not mean in the slightest that you can justify that of person 100. The latter could be the proof that God is evil or that we are right to take the risk of being wrong and just condemn him. We won't discuss how if God would be evil if he were real, then making him real in your head - whether he exists or not - is evil too.
The person saying there is a God will connect that God to morality so she has to show that morality expresses God.
With morality you have different definitions.
Morality is the greatest happiness of the greatest number.
Morality is following a categorical imperative - an act is immoral if life can't function if everybody did it.
Morality is written down for us in a holy book by God.
Morality is the fixed rules that promote the best wellbeing of most people.
Morality is just living out virtues such as temperance, chastity etc.
That is only some of them.
You have a burden of proof to show why any of them is for or against God. Getting it right amounts to getting the right God.
And if you get that far then there is a new problem.
Take big issues like abortion, capital punishment and euthanasia. There is so much more to worry about but you see the point.
If God is say virtue then you know that wrongly thinking he blesses say abortion makes that virtue meaningless.
We conclude: The pro-God claim is always made too lightly. The evidence is full of holes and omissions. It is so much simpler to hold all that is, is from brute fact, that there is no divine plan.
APPENDIX:
I say there is a God of love. Does the burden of proof mean I start with the evidence and arguments against him?
ONE ANSWER: It does not matter that listeners might not like it if you do. The fact is showing he is real and showing that arguments against that are equally important. Toss a coin.
ANOTHER: Starting with objections as opposed to supporting my claim? But starting with objections shows I am supporting my claim. It takes extreme confidence in my position to face the bad points first.
As evil, suffering and religious fakery are so serious I should start with the evidence against God. Religion says I must start by throwing sin out and then go on to do good works. It take a negative approach first and so should I.
APPENDIX: IS EVIDENCE FOR GOD REALLY NEEDED?
The religious argue that God is a commonplace doctrine and because it so common giving evidence is unnecessary.
Give it anyway! Plus do they not respect the pagans? Didn't the pagans question their commonplace gods? If they had not there would have been no learning and no Christianity. It is just a tactic for getting critics to keep their thoughts away from the believers.
APPENDIX: SUPERNATURAL OR GOD?
The believer has to argue for a particular type of God. The person claiming there is a God presupposes that God is vitally important. They need to prove that too. This helps avoid bias.
All the unbeliever has to do is argue that there is no supernatural and that takes care of God in all the variations.
Biggest burdens?
The simplest claim does not have a weaker burden of proof than a more complex one. A claim is a claim.
But "There is a God" is a bunch of claims - burdens. "There is no God" also. The former has the heaviest pile. The believer is being too complicated and that is against Occam's Razor. We have listed some of the issues. Atheists do not have anything to compare to that!
APPENDIX:
Some atheists do not deny the existence of God say they lack belief for they see no proper evidence. They are real atheists in the sense that if you ignore a claim as big as God you are effectively showing you think there is none. You are not claiming God is untrue so you avoid burden(s) of proof.
Living without God would seem to be more than a lack but making a positive claim that God does not matter. But it is making that claim to yourself so you don't have to prove it to anybody else. Believers see that God does not matter to you so they have their proof.
Occam's Razor would tell you to lean towards atheism.