What is spiritual immunity? It is being able to have the spiritual reserve to be able to tap into when you are facing a challenge. The stronger your spiritual immunity is, the stronger your ability will be to withstand the challenges. 

After you have ought against these challenges and won, what will happen next?You become stronger because of that challenge, which is amazing because now your body has built an immunity to that specific challenge. 

When we build spiritual immunity, instead of challenges destroying us they actually make us stronger. This is the design of Allah! One of the reasons why Allah sends challenges to the believers is to strengthen them and purify them not to destroy them.