Final answer:
The question seems to reference a specific Biblical passage concerning the Corinthians' beliefs and actions. However, the provided excerpts do not contain adequate information to provide a definitive answer, and the specific passage in question would need to be consulted to answer accurately about what the Corinthians must do to avoid their beliefs being in vain.
Step-by-step explanation:
The question "15:2 The Corinthians beliefs will be in vain unless they did what?" seems to refer to a passage from the Bible, specifically within the context of Christian teachings or early Christian history. The Corinthians' beliefs likely refer to the teachings of the apostle Paul and the early Christians in Corinth. The question is likely seeking an answer pertaining to the virtues, actions, or beliefs that Paul outlined as necessary for a meaningful Christian faith.
However, based on the excerpts provided, it is not possible to determine categorically from this context what the Corinthians must do to avoid their beliefs being in vain. The excerpts discuss various aspects of the Christian faith, including the importance of charity, teaching, and facing tribulation. To answer this question accurately, one would need to reference the specific Biblical passage (most likely from one of Paul's epistles to the Corinthians) that addresses this question directly.