[Read Genesis Chapter 17]
Often times it is hard to obey God’s Word without question or explanation. Abram in chapter 17 has his name changed to the one we are all familiar with, Abraham. The Lord comes to him to renew the covenant he had made with him in chapter 15. This time though, God institutes a covenant sign for Abraham and his descendants.
The covenant sign is of course circumcision. This sign is invasive and extremely personal to both the one performing, and the one receiving the sign. Abraham is given no reason in the chapter as to why the sign is chosen. Abraham, along with all the males in his household, must simply obey and trust they are doing what is good and pleasing to the Lord.
Michael Jr. has a funny video addressing this question. You can follow the link HERE.
We serve a God who is good, perfect, and wise. No matter the cost, we should always submit under the authority of the Word of God.