Pentecost Sunday marks a significant day in the Christian calendar, celebrated 50 days after Easter. It commemorates the descent of the Holy Spirit upon the apostles and other followers of Jesus, as described in the Bible. This event is considered the "birthday of the church" and is a time when Christians celebrate the beginning of the church's mission to the world

Trinity Sunday is the first Sunday after Pentecost to honor the Holy Trinity—the Father, Son and Holy Spirit. Although the word “trinity” does not appear in Scripture, it is taught in Matthew 28:18-20 and 2 Corinthians 13:14 (and many other biblical passages).

Corpus Christi, meaning "Body of Christ" in Latin, is a Christian festival, particularly in the Catholic Church, that celebrates the real presence of Christ in the Eucharist. It's observed on the Thursday after Trinity Sunday. 

Solemnity of Saints Peter and Paul Today is the Solemnity of Saints Peter and Paul. These two saints are celebrated on the same day because Jesus founded his church on Saint Peter and Saint Paul was the greatest evangelist in the history of the church.