to be completely incompatible

• 两种水火不相容的意识形态

  two incompatible ideologies

• 水火不相容的阶级

  incompatible classes

• 两者水火不相容。

  The two of them are like chalk and cheese.

• 集体主义思想和个人主义思想是水火不相容的两种思想。

  Collectivism and individualism are two completely incompatible ideas.