What is the ruling on praying behind an Imam who supplicates for the victory, protection, and martyrdom of the secular soldiers and troops, despite knowing that this is impermissible? Is the prayer valid or void?

We thank the questioner for his religious zeal. We believe that praying behind this Imam is valid, as he is either correct in the permissibility of supplicating for those he supplicates for, or he is mistaken in his interpretation. He would only be considered a transgressor (fasiq) if he were negligent in his error. The predominant opinion regarding the Imamate of a fasiq is that it is valid, and this is the madhhab of the majority. As for the questioner, he should offer advice and invite to Allah in the best manner, while avoiding discord and strife, especially in mosques. He may also pray in another mosque.