why do catholics believe in purgatory

Catholics believe in purgatory because it is taught as a final purification state after death for souls who die in God's grace but still need to be purified from venial sins or temporal punishment before entering the holiness necessary to enter heaven. It is not a second chance at salvation, but a merciful process of cleansing the soul from imperfections, making it ready to face God in heaven. This belief is rooted in scripture and tradition, including biblical references to purification by fire and prayers for the dead, and was formally defined by Church councils such as the Second Council of Lyon in 1274 and reaffirmed in the Council of Trent. Purgatory reflects God's mercy and justice, ensuring that nothing unclean enters heaven while affirming salvation through Christ.