I'm gonna quote Matt because I need my nap:
When did the OT not include girls?
Were girls "circumcised" in the OT? If they were not, then they are cutt off from among God's people, and not allowed to participate in the Passover.
In mentioning infants, some see problems with Females. Females were not circumcised. Would we contend that they are then baptized? Let me say this, forget baptism for a moment. We are jumping ahead because we have not established that children should be baptized at all yet. But I think an important aspect of the Old Testament covenant has eluded you and we should take it up now. Females were circumcised. We know, in certain medical ways, that women can be "circumcised" of sorts. But nowhere in the Old Testament does God command that women are to be circumcised. That woudl be wrong to a certain degree. Read Exodus 12:48, "And when a stranger dwells with you and wants to keep the Passover to the LORD, let all his males be circumcised, and then let him come near and keep it; and he shall be as a native of the land. For no uncircumcised person shall eat it."
Who is not allowed to eat the Passover?
No uncircumcised person.
How then, could females eat of it? If NO uncircumcised person is to eat of it, no one with a foreskin, and women, anatomically do have that in a smaller degree, then what could God be talking about here?
The male is circumcised on the foreskin. It is cut. Covenants, as we know, are cut. When God made a covenant with Abraham he passed through the animal parts and ratified the cutting of the covenant. He passed through the blood of the covenant. Males are cut, and the sign of the covenant is in their flesh. But females, EVERY FEMALE SEED passes through the midst of the covenant every time procreation takes place. The female seed passes through the male procreative organ, right in the middle of the circumcision made in blood. A covenant, then, is cut every time the child of covenant promise is conceived. The reality of it is ratified on her. Females are virtually circumcised by passing through the covenant sign, and the males are both virtually and actually circumcised to continue the sign in the own flesh.
More here pal:
http://www.puritanboard.com/forum/viewthread.php?tid=5685#pid68614