Bashir says that 98 per cent of the Sudanese population is Muslim, and that the new constitution should reflect this.
Speaking to students in Khartoum, he said the official religion would be Islam and that Islamic law would be the constutional source of future legislation.
Under the comprehensive peace agreement signed between north and south, Sudan's constitution recognises "the cultural and social diversity of the Sudanese people".
But many southerners say they no longer feel welcome in the north since the two separated in July.
The General Secretary of the Sudan Council of Churches, says Sudan must recognise religious diversity. Reverend Ramadan Chan Liol adds that it should explicitly protect the non-muslim minority in the north.
Reverend Chan Liol adds he was surprised to hear Bashir claim that 98 per cent of the population is Muslim because the Sudanese census does not ask citizens to state their religion.