Kuwait's appeals court issued the sentence last month against Ahmad al-Baghdadi, 54, a political science professor and columnist, for harshly criticising plans by the education ministry to increase the number of Islamic education lessons in schools.
Under the law, if al-Baghdadi is convicted of an offence during a three-year probation period, he would be required to serve the jail term immediately.
Al-Baghdadi said last month he had quit writing for fear of being sent to jail. He also said he would seek political asylum in a foreign country.
The appeals court ruling will be challenged by al-Baghdadi in Kuwait's Supreme Court, the highest court in the emirate, and the 15 lawyers will represent him.
In an article last June, al-Baghdadi said he sent his son to a private foreign school to escape the backwardness of public education and because he thought "learning music is more important than learning the holy Quran".
Al-Baghdadi was sentenced to one month in prison in October 1999 for offending Islam in a 1996 article in which he claimed the Prophet Muhammad failed in at least part of his mission. But he was pardoned by the amir after serving 13 days.