Does this verse call Muslims to fight against all non-believers?
Answer
Like the whole of Surat al-Tawbah, this verse must be understood in the context in which it was revealed to the Prophet Muhammad ﷺ and his companions, and the passage must be read in a connected way, so it is clear to whom the verses are referring. This verse refers to the idolaters of Makkah who had driven out the Muslims, and who continued to initiate hostilities, including in underhand ways.
There were four months known by the Arabs as “the Sacred Months”, in which fighting was prohibited according to the religious teachings inherited from Prophet Abraham (peace be upon him). However, it was the habit of the idolaters to postpone a sacred month to the following month if they wanted to carry on fighting. This verse and the following verse condemn the polytheists for playing around with God’s decree in this fashion. At the same time, the verse makes clear to Muslims that they have been given permission to fight any of the idolaters who fight them in these months. The fact that this is meant as retaliation is clear from the wording of the verse “...as they fight you…”.
Summary
This verse gave permission to the Prophet Muhammad ﷺ and his companions to fight in the Sacred Months against those idolaters who fought them in these months.