Deputy High Court judge Rowena Collins-Rice decided not to immediately deliver a decision following a two-day hearing in London but instead chose to make a reserved ruling. Premier understands the announcement of a decision could be days, or even weeks, away.
Felix Ngole from Barnsley has claimed him human rights were breached when university bosses ejected him from a postgraduate social work course after he participated in a debate on Facebook.
Outside court, campaigners from Christian Concern which has been supporting Mr Ngole, held placards.
The online exchange, which took place in 2015, centred on a US state official Kentucky who refused to register same-sex marriages.
Sheffield University said it had to consider the 39 year old's "fitness to practise" after he declared that homosexuality was sinful. The institution said Mr Ngole "failed to show any insight into why his view may be problematic".
Representing Mr Ngole, barrister Paul Diamond said his client expressed his views in a "polite and temperate way", adding he is "entitled to express his religious views".
On behalf of Sheffield University, barrister Sarah Hannett said whether or not Mr Ngole was permitted to hold Christian beliefs is not the issue.
Mr Diamond claimed Mr Ngole's comments were presented in a "private/social as opposed to professional" setting, adding: "Mr Ngole's expression of his beliefs was a genuine contribution to an important public debate."