All of these Scriptures are talking about the condition of the HEART of those who are circumcised, they are not forbidding circumcision.
They are merely warnings that salvation does not come through obedience to or the act of circumcision.
I could quote many NT Scriptures that admonish not keeping the law. Does that mean that everything in Deuteronomy should be thrown out? (Most of these laws were for public health reasons.)
Galations 3:23,24 "Before this faith came, we were held prisoners by the law, locked up until faith should be revealed. So the law was put in charge to lead us to Christ that we might be justified by faith. Now that faith has come, we are not longer under the supervision of the law."
You must admit they are discouraging circumcision when they say, "Do not be circumcised"!
Others in the thread have suggested that circumcision is something that Christians ought to do because of their religion. I think the New Testament shows that we are free to either be circumcised or not be circumcised and that there is no religious significance to it.
Since it isn't required and in most cases the medical benefits are marginal at best, I am going to wait and allow my sons to decide what they want rather than slicing bits off them while they're babies.