Final answer:
Water is an effective sign for Baptism in Christianity because it symbolizes purification and transformation, and it is associated with the Holy Spirit.
Step-by-step explanation:
Water is an effective sign for Baptism in Christianity because it symbolizes purification and transformation. Just as water cleanses the body, baptism is seen as a spiritual cleansing that marks the beginning of a new life in Christ. Additionally, water is associated with the Holy Spirit, as seen in the story of Jesus' baptism in the Jordan River, where the Holy Spirit descended like a dove. This connection between water, purification, and the Holy Spirit makes water an effective symbol for Baptism.