When expressing disagreement or opposition to a particular idea or concept, there are several synonyms that can be used instead of the phrase "in opposition to." Some of these include "contrary to," "against," "challenging," "disputing," and "objecting to." Similarly, you could use "dissenting from," "nonconformist," "opposing," "rebelling against," "resisting," or "contesting." Each of these synonyms carries a different connotation, and choosing the right one depends on the specific context and tone of the situation. Regardless of which synonym is selected, it's important to express one's views with clarity and conviction.