In sending the 19 to jail, the High State Security Court on Wednesday overturned a previous court ruling of suspended jail terms, after President Husni Mubarak asked the court to reconsider the case.
The court immediately ordered the 19, who were not present in the court, to be arrested and begin serving their jail terms.
The 19, including two women, were arrested in March 2002 before they were given suspended jail terms in September of that year.
The group's leader Sayyid Tulba was at the time sentenced to three years in jail, while another member of the group, Gamalat Sulayman was given a one-year prison term.
Tulba, a civil servant with the Egyptian Atomic Energy Authority, had declared himself "prophet of our time" and said he had powers to cure incurable diseases.
He claimed to have received letters signed by God and to be able to speak to the angels.
The presiding judge, Gamal Badran said the 19 were guilty of "having adhered to the doctrine of the sect leader, supported him and together practiced his extremist ideas."