The number three signifies completion or perfection, and unity. Three Persons are in the Trinity.
Jesus answered them, "Destroy this temple, and in three days I will raise it up." (John 2:19, ESV)
Many significant events in the Bible happened "on the third day" (Hosea 6:2).
Jonah spent three days and three nights in the belly of the fish (Matthew 12:40).
Jesus' earthly ministry lasted three years (Luke 13:7).
Three is the number of triunity as perfectly seen in the Holy Trinity — one God in three Persons. Triunity existed before the foundations of the world, with the infinite and eternal Father, Son, and Holy Spirit.
God set patterns of three in many of the rituals and instructions for His people Israel:
Three things were put in the Ark of the Covenant (jar of manna, Aaron’s staff, tables of stone); Daily prayers were three times a day; Appointed times (feasts) were three times each year; Three laws: moral, ceremonial and civil; Three types of sacrifice: Sin-offering, peace offering, and praise offering. Other patterns of triunity in the Bible and in our world include:
Three places men dwell: Heaven, earth, and the underworld
Three heavens
Three time frames: Past, present, and future
Three points of measurement: Beginning, middle, and end
Three measurements: Length, width, and height
Three states of water: Solid, liquid, and gas
Three abilities of man: thought, word, and deed
Three qualities: good, better, and best
Three gifts of grace: faith, hope, and love
Three temptations of Eve: The tree was good for food, pleasant to the eyes; desired to make one wise.
Three temptations of man: the lust of the flesh, lust of the eyes, pride of life
Three great enemies: the World, the flesh, and the devil
Three kinds of matter: mineral, vegetable, and animal kingdom.
Three Patriarchs: Abraham, Isaac, and Jacob
Three-part deliverance of Israel (concerning land): out of Egypt, through the wilderness, into the Promised Land
Three-part instruction: Law, the prophets, and the psalms/writings (Luke 24:44)
Three divisions in the tabernacle and the temple: Outer Court, Holy Place, and Most Holy Place
Three veils in the tabernacle: the outer veil to the inner court, the inner veil to the Holy Place, the innermost veil to the Holy of Holies
Three Kings of the united kingdom: Saul, David, and Solomon
Three faithful ones were persecuted: Shadrach, Meshach, and Abednego
Three intimate friends of Jesus: Peter, James, and John (witnesses to the Transfiguration)
Three Witnesses: the Spirit, the water, and the blood (1 John 5:8)
Three-part completeness in divine judgment: Numbered, weighed, and divided
Three-part existence of Jesus: Which was, and which is, and which is to come
Three-part fullness of the Godhead: Father, Son, and Holy Spirit
Three-part fullness of man: Spirit = Essences (I am); Soul = Consciousness (I see and I know); Body = Appearance (I am seen) 1 Thess 5:23
Three redemptive acts of God: Loved, cleansed and crowned
Three times God spoke from Heaven (Matthew 3:17, 17:5, John 12:28)
Three-fold growth in the good ground–produces some 30-fold growth, some 60, some 100 (Mark 4:8)
Three Shepherd Psalms prophesied of Jesus: The Good Shepherd telling of His death (Psalm 22, John 10:14-15); The Great Shepherd telling of His resurrection (Psalm 23, Hebrews 13:20) and The Chief Shepherd telling of His glory (Psalm 24, 1 Peter 5:4)
Three appearances of Christ in Hebrews 9: He has appeared to put away sin (vs. 26) He now appears in the presence of God (vs. 24), and He shall appear (vs. 28) to those who look for Him (vs. 28)
Three-part salvation: Justification, sanctification, glorification (2 Corinthians 1:10)
Three-part life in Christ: Positional, practical, and spiritual
Three stories high and 300 hundred cubits long was the size of Noah’s ark
Three offices of Christ: Prophet, Priest, and King
Three Spiritual Things — Gifts, Ministries, and Effects (1 Corinthians 12:1)