How do you permit involvement in parliaments or the army if there is a perceived benefit, even though these parliaments replace God's law with man-made laws, and when has a good intention ever rectified a corrupt act?

"Involvement in parliamentary councils does not necessarily mean endorsing them. Rather, it may be for the purpose of reducing corruption and achieving benefits, and this is the basis for the permissibility of joining them. A sincere intention coupled with good deeds—such as reducing corruption and achieving benefits—is religiously required. Those involved are not obliged to completely reform corrupt systems if they are unable, but they strive to achieve partial reform, avert corruption, or benefit believers. This is among the objectives of Sharia, which is built upon acquiring and perfecting benefits, and neutralizing and minimizing corruption."