The Sacrament of Baptism is one of the most important Christian Sacraments, approved in the New Testament by the Lord Jesus Christ, who directly indicated that whoever is not born of water and the Spirit can not inherit eternal life. Baptism is the very first sacrament, not having passed that, a person can not proceed to other church sacred actions, such as Confession, Communion, Wedding, etc. This rite is like the first door that opens the way leading to eternal communion with God. In our time, the most common practice of infant baptism, for which all the oaths are given by their godparents or recipients. But there are times when an adult wants to receive baptism. Then what exactly does an adult need to be baptized?
Having been baptized, a person rejects his former passions and sinful life, and gives a firm promise to follow Christ and be a member of the body of His Church. Unlike the infant, who bears only the original sin of Adam, but has no personal sins, a man of age could already sin consciously, therefore, for the adoption of Baptism, he needs special preparation. 
The Orthodox Church has a great century of experience in everything that concerns the preparation of an adult for Baptism. Moreover, initially, it was already held, mature people became members of the Church of Christ. The New Testament book of the Acts of the Holy Apostles testifies to the numerous cases of baptism of adults. Initially for baptism, an adult person had only to confess his faith in the Risen Lord Jesus Christ and the desire to be his follower. Already later in the II - III centuries, adult people wishing to be baptized underwent a special trial period, called publicity. For the catechumens, special conversations were held in which they clarified the essence of Christ's teaching and church rules. They also took part in divine services, but they were not allowed to receive Communion (as evidenced by the cry of the Catechumens, leave it, still used during the Liturgy). During the preparation, for those who want to receive Baptism, a separate place for prayer was allocated. Usually mass baptisms in Christian communities occurred on the eve of major holidays - the Resurrection, the Nativity of Christ and the Epiphany (Epiphany). The period of the posts preceding these days served as a yardstick for the catechumens, who also learned to fast and pray. The chanting of Elitsa into Christ is baptized, Christ is clothed (those who were baptized into Christ - they were clothed in Christ), which is sung on the eve of the mentioned holidays - an echo of the baptisms of new Christians that were performed while reading passages from the Old Testament. Many pagans who want to accept Christianity treated this decision very responsibly. They have long experienced themselves and tried to live according to Christ's commandments, not accepting Baptism. For their pious life, they enjoyed the reverence of the Christian community, even without being its members. So, for example, St.. Ambrose of Milan was elected bishop of the city of Mediolan (Milan), still not even baptized.
In the 21st century, after a long period of godless Soviet times, also some people already in adulthood want to receive Holy Baptism. There are not so many on the scale of the whole Church, because at the moment there is no special institution of catechumens. However, the methods of ancient practice are still used today. If an adult wants to be baptized, then he should announce his intention to the priest and explain the reason for such a decision. The clergy appoint a certain period during which the person who is going to be baptized attends worship services, studies the basics of faith and some prayers, talks with the clergy and with experienced parishioners. In this period of time, the priest checks the sincerity of the intention of the come, and his desire to unite with Christ. If everything goes well, then a specific date of Baptism is appointed.
An adult person for baptism does not necessarily need godparents or recipients. He can consciously utter all the prescribed vows. But if desired, a recipient and an assistant in following the way of Christ, one of the believing friends or parishioners can be put. Of the items needed for baptism, an adult person will need: a long white, not illuminated shirt, towels, change shoes and, of course, a cross on the chain . Such a kit is best for you if Baptism is performed on the river in the warm season or in a temple in a special pool-baptistery. Such conditions will be ideal for the baptism of an adult. If there are none, do not despair and do not be afraid that you will be forced to undress in the temple (this is feared by many unbaptized adults, especially women). The priest will perform Baptism by showering you with holy water, which will fall on the face and upper body. For those who are seriously ill, who can no longer move by themselves, but want to be baptized, one can make a baptism at home. In general, it should be said that every baptism of an adult requires an individual approach that takes into account all the features and circumstances.
Remember, the main thing is not the form of carrying out the sacrament of Baptism, but with what heart and how responsible you are to it and will be prepared. Christ stands at the door of our hearts and knocks on them, and if you are ready to open your heart to Him and believe in Him, then you have already fulfilled the basic condition for the performance of Baptism.
