Complex sentence: Whitsun, also known as Pentecost in the Christian calendar, is the seventh Sunday after Easter and commemorates the descent of the Holy Spirit upon the disciples of Christ (Acts of the Apostles chapter 2).
Split into simpler sentences: Whitsun, also known as Pentecost in the Christian calendar, is the seventh Sunday after Easter. Whitsun commemorates the descent of the Holy Spirit upon the disciples of Christ (Acts of the Apostles chapter 2).