So you think baptism came in place of circumcision, and is the "Christian equivalent". Here are a few points for you to ponder (and respond to, if you can):
1. Males only were subjects of circumcision; but males and females are subjects of Christian baptism. "Every male child among you shall be circumcised." The Apostles "baptized both men and women."
2. Circumcision was ordained to be performed on the eighth day--the first day of the second week of every male child. Does your church always use the same day in dispensing the rite of infant baptism?
3. Adult males circumcised themselves. In your church do adult believers baptize themselves?
4. Infant males were circumcised by their own parents. Do Catholic parents baptize their own infant children?
5. Infant and adult servants were circumcised neither neither because of flesh or faith, but as property. Does infant baptism ever occupy this place?
6. Circumcision was not the door into the Jewish church. It was four hundred years older than the Jewish church, and introduced neither Isaac, Ishmael, Esau, nor Jacob into any Jewish or patriarchal church. It never was to any Jew, its peculiar and proper subject, an initiatory rite. They were not circumcised to make them Jews, but because they were Jews. Why, then, call infant baptism an initiatory rite?
7. The qualifications for circumcision were flesh and property. Faith was never propounded, in any case, to a Jew, or his servants, as a qualification for circumcision. But does your church ever say "If you believe with all your heart, you may" (be baptized)?
8. Infant baptism is frequently called a dedicatory rite. Believers may dedicate themselves, but cannot dedicate others to the Lord in a Christian sense. In the Jewish sense, however, infants were dedicated to the Lord. But dedication was never performed by circumcision. The circumcised were afterwards dedicated to the Lord: Numbers viii. 13-21. Why, then, make baptism a dedicatory rite in place of circumcision?
9. Circumcision, requiring neither intelligence, faith, nor any moral qualification, neither did nor could communicate any spiritual blessing. No person ever put on Christ, or professed faith, in the act of circumcision.
10. Circumcision was a visible, appreciable mark, as all signs are, and such was its chief design. Does baptism fill its place in this respect? You might want to consider Paul's epistle to the Ephesians where he indicates the identifying mark the Christian bears is the indwelling Holy Spirit.
11. The duty of circumcision was not personal, but parental. Parents were bound to circumcise their children. The precept ran thus--"Circumcise your children." But in baptism it is personal--"Be baptized, every one of you."
12. The right of a child to circumcision, in no case, depended upon the intelligence, faith, piety, or morality of the parents. Why, then, in substituting for it infant baptism, are its benefits to infants withheld from them, because of the ignorance, impiety, or immorality of their parents? Does infant baptism exactly fill the place of circumcision in this particular? Or even come close?
13. Circumcision was a guarantee of certain temporal benefits to a Jew. Does baptism guaranty any temporal blessing to the subject of it?
14. It was not to be performed in the name of God, nor into the name of any being in heaven or earth. Why, then, on the plea of coming in the place of circumcision, is any infant baptized in or into the name of Father, Son, and Holy Spirit?
15. The subject of circumcision was a debtor to the whole law. Is this true of every subject of baptism?
16. Jewish Christians continued to circumcize their infants. Why, if baptism had replaced circumcision?
You alluded to Paul'scomments in Colossians. You overlooked v .13. Consider vs. 11-13:
Colossians 2:11-13 (New American Standard Bible)
11. and in Him you were also circumcised with a circumcision made without hands, in the removal of the body of the flesh by the circumcision of Christ;
12. having been buried with Him in baptism, in which you were also raised up with Him through faith in the working of God, who raised Him from the dead.
13. When you were dead in your transgressions and the uncircumcision of your flesh, He made you alive together with Him, having forgiven us all our transgressions,
Paul informs us the subjects of baptism were also raised up with him through faith..... And they were forgiven their transgressions (plural), obviously not Adam's sin. What faith and sins do your infants have, and what faith was exercised and what sins were forgiven in circumcision?
And what of Peter's statement in 1 Peter 3:21:
1 Peter 3:21 (New American Standard Bible)
21. Corresponding to that, baptism now saves you--not the removal of dirt from the flesh, but an appeal to God for a good conscience--through the resurrection of Jesus Christ,
I ask you, does the infant your church baptizes make an appeal to God? How? Did the Jewish infant? Only a believer can do this. And I have it on good authority Peter has as much authority as your Pope!

I expect, as is your practice, for you to go flying off to something irrelevant to the points I have made instead of responding, but I have hope, otherwise there is no point in continuing.