Christian Unions at Edinburgh, Heriot-Watt, Birmingham and Exeter universities are now seeking legal advice amid accusations that they are excluding non-Christians, promoting homophobia and discriminating against those of transgender sexuality.
Edinburgh University chiefs banned the Christian Union from running its PURE course which promotes marriage as the best setting for a sexual relationship. The ban follows complaints from other students that the course was homophobic.
Meanwhile, the Exeter Christian Union has had its Student Union bank account frozen and has been banned from free use of students' guild premises or advertising within guild facilities.
Dr Frost criticised the university authorities for denying the Christian Unions the right to freedom of speech, which he called "one of the most hallowed and important aspects of a free society".
"The loving, serving and gracious ways in which the Christian Unions have carried out their ministry over the last 80 or more years is to be applauded. The fact that they are now being pushed off of university campus property, and out of the mainstream of student life is a great tragedy," he said.
Dr Frost offered his support to the Christian Unions' legal campaign to be fully restored on the campuses as a legitimate university society.
"This is not a sudden or angry reaction; they have been dealing with increasing oppression over the last five years," said Dr Frost.
"If we cannot have Christian organisations run by Christians, and traditional bible believing teaching given on student property one must ask, 'What kind of world are we entering?'"
He added, "I commend those who will say political correctness has its place but there are even more vital things at stake here."