The obligation of establishing justice between Muslim and non-Muslim workers

I have two equally capable workers, one of them is a Muslim and the other is a Kafir (non-Muslim). I am asked to assess their work. Is it permissible for me to act unjustly to the Kafir because of his beliefs? Answer: You must establish justice between them. However, it would be best to fire the Kafir, even if he is more efficient, as Muslim workers are more blessed, even if they are less efficient, let alone equally qualified with non-Muslims. It was authentically reported from the Prophet ﷺ that he advised expelling the Kafirs out of the Arabian Peninsula, so that there remains only one faith in it.) May Allah grant us success! [Majmoo ’al-Fataawa Ibn Baaz, Vol.: 23; pg. 218]