(1) What is purity / impurity? (2) Why does God require the maintenance of purity? (3) What is the logic of the laws we encounter related to purity, specifically the food laws?
To me, purity and impurity can be quite relative concepts when it comes to their definitions. Nevertheless, purity is definitely related with morality and good behavior, while impurity is more commonly linked with the opposite. Purity, in God’s eyes, usually refers to a life that follows the Ten Commandments, an that despite obstacles on the way, remains being a life full of grace and obedience to the Lord. Impurity, on the other hand, refers more to the dissonance of what the Lord asks of us and how we behave in response or according to. Impurity is often related to “dirtiness,” given that dirt does not have a nice connotation or is not often referred to when giving out positive commentary.
God requires the maintenance of purity because he wants us to be good children of His; and, in order to do so and receive the blessing of being someday with Him in Heaven, we must make sure to behave in accordance to His commandments. Moreover, as children of the Lord, and made in His image and likeness, we are expected to behave in the same ways He would in our position. Conserving pure souls is important given that in a world full of obstacles, we must learn to face them and not let ourselves go with the flow.
Therefore, the laws created by God in regards to purity are there in order to be our guidance through our walk in life. Whenever we feel lost, or in any given moment, we can appeal to these laws and make the best out of the situation we find ourselves in. The food laws, moreover, also represent ethical standards, where we should only be able to eat certain foods, and refrain ourselves from those the Lord explains should not be consumed.
A Theological Mindset 