Entering the Covenant of Christ

Colossians 2:11-12 NIV 
11In him [Jesus Christ] you were also circumcised with a circumcision not performed by human hands. Your whole self ruled by the flesh was put off when you were circumcised by Christ, 12having been buried with him in baptism, in which you were also raised with him through your faith in the working of God, who raised him from the dead.

Genesis 17:9-14 
9Then God said to Abraham, “As for you, you must keep my covenant, you and your descendants after you for the generations to come. 10This is my covenant with you and your descendants after you, the covenant you are to keep: Every male among you shall be circumcised. 11You are to undergo circumcision, and it will be the sign of the covenant between me and you. 12For the generations to come every male among you who is eight days old must be circumcised, including those born in your household or bought with money from a foreigner—those who are not your offspring. 13Whether born in your household or bought with your money, they must be circumcised. My covenant in your flesh is to be an everlasting covenant. 14Any uncircumcised male, who has not been circumcised in the flesh, will be cut off from his people; he has broken my covenant.”

Joshua 5:1-9 
1Now when all the Amorite kings west of the Jordan and all the Canaanite kings along the coast heard how the Lord had dried up the Jordan before the Israelites until they had crossed over, their hearts melted in fear and they no longer had the courage to face the Israelites. 2At that time the Lord said to Joshua, “Make flint knives and circumcise the Israelites again.” 3So Joshua made flint knives and circumcised the Israelites at Gibeath Haaraloth.4Now this is why he did so: All those who came out of Egypt—all the men of military age—died in the wilderness on the way after leaving Egypt. 5All the people that came out had been circumcised, but all the people born in the wilderness during the journey from Egypt had not. 6The Israelites had moved about in the wilderness forty years until all the men who were of military age when they left Egypt had died, since they had not obeyed the Lord. For the Lord had sworn to them that they would not see the land he had solemnly promised their ancestors to give us, a land flowing with milk and honey. 7So he raised up their sons in their place, and these were the ones Joshua circumcised. They were still uncircumcised because they had not been circumcised on the way. 8And after the whole nation had been circumcised, they remained where they were in camp until they were healed. 9Then the Lord said to Joshua, “Today I have rolled away the reproach of Egypt from you.” So the place has been called Gilgal to this day.

Look up the definition of the word “Covenant”. 
In Genesis 17, the Hebrew people were given - through Abraham - circumcision as a physical mark of their identity as being in a covenant relationship with God. How serious was this circumcision sign that the Hebrews entered into covenant with God?

If baptism is described in Colossians as the circumcision of Christ, what does it tell you about baptism as the New Testament mark of entering into covenant relationship with Christ?

How should we view the fact that we have entered into this holy covenant with God