What do Christians/Catholics believe holy water does?
HOLY WATER – Sacramental blessed by a priest, invoking God’s blessing on all who use it. Blessed water is a symbol of spiritual cleansing, and its use is advised in moments of physical danger and against temptations from spiritual enemies. I is common practice to dip one’s fingers in holy water and reverently make the Sign of the Cross as one enters a Catholic church, and it is recommended for use in the home. Holy water is used in all blessings. There are, besides ordinary holy water, baptismal holy water, used with chrism in the conferring of public baptism, and Easter water specially blessed for use during the paschal time.