Pentecost Sunday marks the birthday of the church when the Holy Spirit fell upon believers, baptizing them with fire. This 'second blessing' follows salvation and transforms believers from within, leaving a visible imprint on their hearts. At the original Pentecost, the Spirit descended like a violent windstorm, appearing as tongues of fire and enabling disciples to speak languages they never learned. This event reversed the division of language at the Tower of Babel, unifying believers in the Spirit with humility and compassion rather than pride and selfishness. A truly Spirit-filled church points to Christ rather than itself, and carries the Spirit's presence beyond church walls into everyday life.