Tieflings are hellspawn. It's literally a bloodline. You don't even understand that racism in dnd is 100 percent due to the Gods that made them and how they interacted with each other. You know the Gods that literally made each and every race.
I've explained, in simplified terms, the established lore surrounding tieflings. They are plane-touched; they are not hellspawn. It would be very easy for you to fact-check me and get yourself properly informed, if you were interested in doing so. If you want to continue to reiterate and double down on your ignorance as a form of argument, that's up to you. There are many ways that tieflings can come about, and direct blood lineage is only one of them (though since Asmodeus' gambit, it is tractably the most common example). Regardless of the source of the infernal legacy, in tieflings it is diluted enough that it has no impact upon their individual personhood, beyond visual physical traits, and sometimes a few minor powers. They are perhaps more vulnerable to influence and temptation by the hells, perhaps, but that is mostly as a result of their social circumstance and the prejudice they regularly face.
I wasn't even going to point out any of your bs, but you are pushing it.
If you have an issue with my conduct, or what I'm saying, then please, by all means, air it - or send me a message. Posturing like that serves no purpose. I am doing my best to keep things civil and to be as open-handed in my discussion as I can; I'm mostly only really citing established lore.
To Dexai,
Yes and no - that was a singular big power move by Asmodeus, when he claimed his godhood by wresting it from azuth (I believe). He 'claimed' all tieflings as his, and in that moment everyone with any infernal legacy was transformed into an Asmodeus teifling. However, it was a one-off power move. Since that point, tieflings have continued to be born and to arise from all of the normal other means and methods - individual other fiends have made their own bloodline pacts again, and planar contact with the hells or the abyss has given rise to those various types of naturally occurring tieflings again as well. Asmodeus tieflings, right now, are by far and away the most common and populous type, because of what Asmodeus did, but certainly since the second sundering, many other appearances have begun to creep in again.