I believe the best approach to reading the Bible is to assume that it is meant to be taken literally unless something in the text itself suggests otherwise. Obviously, dreams and visions will be characterized by symbolism. And parables are symbolic stories. And psalms will use poetic expressions that are not meant to be literal. But most of the Bible is written in narrative form that is safest to take literally.
Because if you assume the Bible should be taken figuratively, then your interpretive paradigm becomes unloosed from reality, and you can start giving the simplest stories the most outlandish interpretations. There’s really no limit to how far fetched one’s imagination can take this. And the end will be that of someone who has been ever learning, and never coming to the knowledge of the truth - II Timothy 3:7.
Now, your heading to this post began with “Why circumcision” - and that was really what I meant to respond to. And I think this topic will illustrate what I was saying about taking the Bible literally for the most part.
Circumcision of Jewish boys on the 8th day of life was a picture of the circumcised heart that every Jew was expected to have in the sight of God. His circumcision was a sign of his righteousness (Romans 4:11) - but the sign was only real if the righteousness was real.
Being circumcised pictured a heart free of the flesh - being uncircumcised pictured a heart dominated by the flesh. How exactly did circumcision picture this? Well, several ways.
Circumcision is painful - like repentance. Leviticus 26:41 says that uncircumcised hearts must be humbled. And Christ uses the sword of the Spirit to cut through the heart of flesh - Psalm 51:10.
Circumcision was Abraham’s seal of righteousness (Romans 4:11) - but now we are sealed by the Spirit (Ephesians 1:13). The seal of the Spirit identifies you with the covenant people, separates you from the world, makes you different.
Circumcision is done to you. No 8-day-old child can circumcise himself. Colossians 2:13 says that we are circumcised by Christ.
Circumcision happened concurrently with your birth - on the eighth day (the day of resurrection; the day of the new creation). The new birth is what gives you a new heart, a spiritual or circumcised heart.
Circumcision is personal - no one really knows your heart but you and God - and possibly those closest to you. Your parents may know your true heart - your spouse may. Still, you can hide your true heart from most people, but not from God.
The eighth day when a child was circumcised was when he also received his name. And at salvation, Revelation 3:12 says we receive our new name from God.
I hope these thoughts will help you appreciate better the reason behind circumcision in the Abrahamic Covenant.