The only way of entry into the Orthodox Church is through an Orthodox Baptism! Holy Baptism in the Orthodox Christian Church is unique and unrepeatable. Only baptised Orthodox bishops or priests can baptise another person, making them members of the Body of Christ. It has to be performed with triple and full immersion of the person being baptised.
The baptismal water is blessed by the priest; supplication is made for the descent of the Holy Spirit into the water. The water is then not mere water but holy water filled with the grace of the Holy Spirit. This is the spiritual womb that Christ said we should be born again, by water and by the Holy Spirit. The person is then immersed three times in the name of the Father, and of the Son and of the Holy Spirit. This is our spiritual birth in the Holy Spirit. This is how we can become truly members of the Body of Christ.