De or het relativisme?

The correct Dutch article is:

het relativisme

Rule Words ending in -isme: almost always het. See the rule
Meaning (Dutch) (filosofie) opvatting dat alles betrekkelijk is

How to use relativisme

the relativismehet relativisme
this relativismedit relativisme
that relativismedat relativisme
our relativismeons relativisme
your relativismejouw relativisme
every relativismeelk relativisme
which relativisme?welk relativisme?
a big relativisme / the big relativismeeen groot relativisme, het grote relativisme

Dutch words ending in relativisme

cultuurrelativisme

In compound words, the last part decides the article. See the rule

Meaning, plural, diminutive, pronunciation and translations: WikiWoordenboek (Dutch Wiktionary) (CC BY-SA 4.0). Example sentences: Tatoeba (CC BY 2.0 FR).