The Greek noun antithesis (ἀντίθεσις) means opposition, contradiction, or what is set against. It is the source of the English word "antithesis." It appears once in the New Testament in 1 Timothy 6:20, where Paul warns Timothy to avoid "godless chatter and the opposing ideas (antitheseis) of what is falsely called knowledge."
Paul's use of antithesis in 1 Timothy 6:20 targets proto-Gnostic and speculative teaching that set itself against sound doctrine. The term may even reference a specific work — Marcion's later work was called "Antitheses" — but Paul's concern is broader: any system of thought that positions itself as superior wisdom against the simplicity of the gospel. The word warns that not all intellectual opposition to the faith is honest inquiry — some is fundamental hostility dressed in philosophical language. Timothy is to "guard what has been entrusted" — the deposit of apostolic truth — against the antitheses of false knowledge. This remains a perennial pastoral challenge.