Youre gonna have to walk me through this: according to the verse, we need(ed) to be "reconciled" to God. I assume this means that we are in His debt vis a vis sin (Original or otherwise). So re debt, the debtor has two paths towards recolliation: forgiveness or atonement. If God wants to forgive us-- being the omnipotent being that He is -- He just clears the debts, no questions asked ... you know like we do when our children f*@&% up. I.e. there ain't no need for a mediator. Atonement, on the other hand, requires a repayment of a debt. In the passages you quote, this repayment, the atonement is taken care of by Jesus. And the atonement is made "through blood on the cross." So, your exegesis is in a bind: you claim both that God forgives our sin (I.e. rents the veil in the Temple before Jesus expires on the cross as in Luke, if I remember correctly), and at the same time that God accepts atonement for our sins with Christ's blood as tender (i.e. rents the veil in the Temple after Jesus expires on the cross as in Mark). Forgiveness and atonement are mutually exclusive ideas, and this is made explicit in this context by the discrepancy about when the Temple veil was torn.
So, again, walk me through it. I just can't understand why an omnipotent diety would demand atonement, a blood sacrifice of his own son, when both Jesus and lowly sinners like myself can forgive "for they no no what they do," etc.