Dear GraceCoolidge,
Well, Catholics don't usually use the words "born again," (I usually don't) but to be baptized is to be "born from above," or put differently, to be incorporated into God's family.
Baptism is about spiritual birth, about entry into the spiritual family of the Church, which is the Body of Christ.
People who are not baptized have souls, but those souls are dead, from the effects of original sin.
The reason why we acknowledge ONE baptism is because we believe that one may be validly baptized only once. Baptism creates an indelible mark on the soul. Again, this is because the one baptized is incorporated, through being "born from above" into the family of God, via the work of Jesus Christ on the Cross.
It is said that even the Catholic who is damned will be recognizable, in Hell, as a Catholic, as one baptized.
sitetest
I don't disagree with your statements, but using that definition, everyone baptized would be born again. When I hear someone refer to a "born again Christian," I thought they were referring to a spiritual process apart from baptism. As far as Catholics are concerned, I don't disagree that one's baptism is a spiritual birth, but to me (and I think to most people), that isn't what is meant when you refer to a "born again Christian."