I am tired of being accused of making claims. I am not making any claims because I have nothing to claim since I am a nobody.
The Messengers of God made claims in their scriptures. The main things they claimed were that:
1) They were sent by God
2) That God communicated to them
3) That God exists
I believe their claims but I am making no claims since I have nothing to claim.
Its a fine line and often it gets mixed up. Obviously as you say in regards to the things you mentions here are the claims of the messengers and you as such are not required to prove them right to others.
But often the issue will be in regards to someone asking or wanting a clarification of how a person know that their claims are true. Which means that these are basically claims:
The evidence that supports the claims of any alleged Messenger of God is as follows:
1) Their Person (their character, as demonstrated by the life they led)
2) Their Revelation (the history, which is what they accomplished on their mission from God)
3) Their Words (the words that were attributed to them in scriptures, or what they wrote)
Its sort of the same as when a biologist say that evolution is true and someone might question the claim, such person wouldn't simply throw their hands in the air and say that the burden of proof is on Darwin, because he made the "claim".
So obviously the burden of proof that Baha'u'llah was a messenger of God is on him, but in the same way as with the biologist, if you claim that it is true, then you do have a burden of proof of how you know that. But obviously it is not exactly easy to prove that, whereas the biologist would very easily be able to demonstrate why evolution is true, because there are so many evidence for it, compared to whether or not Baha'u'llah were a messenger or not.
So one could say that it is probably more reasonably for the biologist to claim that evolution is true, than it is for you to claim that Baha'u'llah were right/true. Obviously you are free to believe it, but it will simply be a believe, just as people believing that Jesus were the son of God.
All this makes logical sense if people could only remove their bias and think about what I just said. Of course, it would require atheists to think differently than they have always thought about claims and evidence and see another point of view that they had never considered.
I don't think people should change their point of view on what a claim and evidence is. If you look at the definition of claim:
1. state or assert that something is the case, typically without providing evidence or proof.
But there seem to be a huge difference in how people understand what evidence and proofs are and what it means whether these are good or weak, or whether they can even be considered evidence at all.
For example in my opinion, none of those (3) you mentioned above I would consider evidence at all, because I don't see how one could draw a line or conclusion to that meaning that they are a messenger of God.