The notion that professing to lack belief in something presupposes you had to believe in the existence of that to begin with (and moreover, that the object had to be real also) falls completely on its face.
To show that respect for others’ beliefs doesn’t mean the weakening of one’s own, but recognizing the dignity and conviction of others who are as certain of their certainties as you may be of yours, and being OK with that.
I can't claim to know whether every Memorial Day or Veterans Day observance excludes non-believers from the official observance when religious invocations are done, but it is fair to say we aren't taken note of generally.
In America it has turned into functionally an over the top cosplay party with virtually no religious connotation for most people, and the secular practice has spread to England where parents grump over having to buy bags of candy to gift the marauding disguised child extortionists as do their American counterparts.
Is there any good reason to think any particular god, currently worshiped or not, explains the data stream at all, let alone better than a naturalistic framework?