Antonyms for the phrase "being foundation for" include destabilizing, weakening, undermining, dismantling, and destroying. When something is the foundation for another, it means that it serves as a base or support for that thing. Therefore, antonyms would be words that mean the opposite of providing support or stability. These words suggest a lack of coherence, strength, or stability, indicating that the thing in question may be under threat or in danger of collapsing. Thus, it's important to choose the right words to express what we mean accurately and precisely, especially when conveying important information or discussing important ideas.