The Creed is recited in the Divine Liturgy and in personal prayer. It confesses the Father, the Son, and the Holy Spirit; the Incarnation, Cross, Resurrection, Ascension, and Second Coming of Christ; the Church; baptism; the resurrection of the dead; and the life of the age to come.
Why it matters
The Creed is not a substitute for the whole life of the Church, but it is a boundary and summary of the apostolic faith. It teaches that Orthodox Christianity is not vague spirituality, but a concrete confession of God and salvation.
The Holy Spirit
In Orthodox liturgical use, the Creed confesses the Holy Spirit as proceeding from the Father. Discussions about later Western additions to the Creed can become complex; beginners should first learn the Creed as it is prayed in Orthodox worship.
Praying the Creed
The Creed can be read slowly as prayer, not merely studied as doctrine. It forms the mind, steadies the heart, and connects personal faith to the faith of the Church.
This is an introductory explanation, not a full history of the councils or later theological controversies.