How can, "I don't believe in gods" be wrong? That is the sine qua non of atheism. That is what is true about all atheists, and if it's not true for a given person, he's not an atheist.
Not a problem for the humanist, who has eliminated the problems religious belief causes for believers. Religion is never more important than love for the humanist, and never corrupts his understanding of what love is and entails. Likewise with justice and mercy. The humanist doesn't use such words to describe a deity that requires blood sacrifice and is willing to torture forever without the possibility of parole for the mistake of not guessing to believe in a particular god. I think you'll find the words and deeds of humanists to be more in accord with one another than those of the believers who claim the Golden Rule for themselves as they go on demeaning and oppressing various groups like LGBTQ+, women, and atheists.
Does that only apply to atheists? How about theists doing exactly that? Do you ever give them that message? I don't, because I don't consider their claims that gods exist offensive. But I also don't give that message to fellow atheists, even those who insist that gods don't exist, because why would I? Should I feel insulted?
He gave his argument. It's an ad ignorantiam fallacy if you take it at face value. To paraphrase, "Nobody has proved that gods don't exist to me, so I conclude that they don't."
Religion and authoritarianism are the chief antagonist to the humanist vision, which is naturalistic and pro-life (in the fullest sense of the phrase, not its most embryonic sense). Abrahamic religion teaches that the world is base and transitory and was created as a playground for man. Let's hear from Christians in government:
- "We don't have to protect the environment, the Second Coming is at hand" - James Watt, Secretary of the Interior under Reagan (note his position and responsibilities)
- "My point is, God's still up there. The arrogance of people to think that we, human beings, would be able to change what He is doing in the climate is to me outrageous." - Sen. Inhofe, R-Okla
- "The Earth will end only when God declares it's time to be over. Man will not destroy this Earth." - Rep John Shimkus, R-Ill.
You won't find comments like that coming from humanists.
Every believer is playing God when he takes the liberty of speaking for one. It's the people he accuses of wanting to be gods by rejecting religions that want to control him with their unevidenced claims about gods who are humbly making the world a better place for all, including theists. Freedom of (and from) religion is a humanist value.
If your experience is so easily blighted, it isn't spiritual. You can't blight this humanist's spiritual experience of nature.
My conscience is the only source of my values. It issues moral imperatives as well as rewards for compliance and guilt and shame for violation. One learns how to navigate that to maximize satisfaction. I suppose that you will claim that the moral intuitions of my conscience come from a god, but I have no reason to believe that.