The convict, also known as Salim Mohammed, was teaching at a school in Kwale, about 60km (40 miles) from Mombasa.
But he was acquitted of being a member of al-Shabab and recruiting for the Islamist militant group which is headquartered in neighbouring Somalia and has been increasingly targeting Kenya.
Children testified that he taught them that Christians were unbelievers who should be killed.
Some of the children converted to Islam after being influenced by him.
He was also an imam at the Masjid Jihad or Jihad Mosque.
Contrary to earlier reports, the court in Mombasa city acquitted him of being a member of militant Islamist group al-Shabab, and recruiting for it.
The group, which is linked to al-Qaeda, has increasingly targeted Kenya.