Das Weihnachten klingt total falsch. Bisher habe ich das noch nie gehört. Die Weihnachten klingt richtig.

We should probably stick to English in the discussion, since this is a mostly English-language site. (Translation: "Das Weihnachten" sounds totally wrong. Till now I've never heard it. "Die Weihnachten" sounds right.) But to answer your comment, the singular "Weihnachten" gets recognition from online dictionaries. Leo.de says it's a singular noun, though the plural is also "Weihnachten." Langenscheidt also gives it as a singular neuter noun.

Maybe what's going on is that it's almost always used in the plural form, which for reasons going back into history is different from the plural of "Nacht." That covers most of what's odd, though it's still weird that it's used in the plural and that Christmas Day is a "night."

We should probably stick to English in the discussion, since this is a mostly English-language site.

Nö. Wir diskutieren hier über die deutsche Sprache, also kann ich auch deutsch schreiben. Englisch ist bereits viel zu überrepräsentiert und ungeeignet für genaue Aussagen, da englisch Wörter oft zu unpräzise sind.

Einzahl würde »Die Weihnacht« richtig klingen. Würde jemand zu mir »Das Weihnachten« oder »Das Weihnacht« sagen würde ich denken das Deutsch eine Fremdsprache für ihn ist.

Mag sein, dass der Duden, Leo, Langenscheidt oder sonst wer das anders sieht, eventuell ist es auch nicht in jeder Region gleich. Dennoch, niemand der hier, wo ich lebe, in einer deutschsprachigen Region, aufgewachsen ist, würde »Das Weihnachten« sagen.

Ich bin, wie du vielleicht an meiner Sprache siehst, kein Experte der deutschen Sprache. Es ist einfach so, dass für mich, jemand der deutsch als Muttersprache hat, »Das Weihnachten« komplett falsch klingt.

Let's not confuse the use of articles with grammatical genders.

IF an article is to be used, then the gender becomes relevant for the choice of the article. Otherwise it's best to stop equating der/die/das with the grammatical genders for that particular word. "Weihnachten" goes without an article in German Standard German, Austrian Standard German, and, I believe, also in Swiss Standard German. Any exotic, regional usage with an article can only confuse the non-native speaker who is still working hard to master one of the standard forms of the language. Similarly, "die Weihnacht" should be treated as a different word with a different meaning, different gender, and different rules for the use of an article; it's roughly equivalent to "die heilige Nacht", the single night during which Jesus was born.

Jesus. Not "the Jesus".

"Die Weihnacht", a single night starting by the sunset on 12/24, marks the beginning of "das Weihnachtsfest", the multi-day period also known as "Weihnachten". In German-speaking countries, at least Saint Stephen's Day (Boxing Day) is understood to be part of Christmas, and not a holiday following Christmas. Hope that this helps to clarify that "die Weihnacht" and "Weihnachten" are in no way synonyms.