Communion
Communion
[Cueball and Danish are taking a stroll.] Cueball: How was Christmas? Did you go to church?
Danish: Yup. We celebrated the birth of a child, then we ate of his flesh and blood.
[Silence from Cueball.]
Danish: Seriously hope we got the right child this time.
This comic plays on the Christian doctrine that the Holy Communion bread and wine are Jesus' flesh and blood. It is based on the words of Jesus from the synoptic gospels and Paul's first epistle to the Corinthians during the Last Supper , today used by the priest as Words of Institution . According to the Roman Catholic doctrine of transubstantiation , as well as in the Eastern Christian tradition, the substance (using the Aristotelian concept that all things have an accident, or physical make-up, as well as a substance, or true nature/purpose) of the bread and wine change to Jesus' flesh and blood, while their accidents remains the same. Many people, including many Catholics, believe this concept means the bread and wine literally turn (i.e., their accidents changes) into Jesus' flesh and blood during the ceremony. Some Protestant denominations reject this doctrine, both its actual and misunderstood application, with some taking the words as wholly symbolic of Jesus' sacrificial death and others believing the bread and wine create a real spiritual connection to Christ but do not change their substance.
In the second panel, Danish accurately describes what would happen at a traditional Christian Christmas service, though in such a way as to make it sound macabre.
After walking and thinking in panel three, she makes it more macabre when worrying that they, again, may have gotten hold of the wrong child for the sacrifice needed to drink blood and eat flesh.
The title text further spoofs the common understanding of the doctrine of transubstantiation and elaborates on Danish 's concern in the last panel by supposing that the act of taking a sip of wine during Holy Communion turns that wine into the blood, not of Jesus, but of a decades-old murder victim.  Alternatively, the title text could be interpreted as saying that the wine actually acquires Jesus' DNA, and that Jesus was "killed" in the 1970s.  The police, who investigated Jesus' 1970s death, would then have his DNA on file.
It should be noted that saliva includes DNA, so the positive result may be the DNA from the person who spit the wine/blood out and does not necessarily mean that that person was murdered by the church in order to prepare the wine/blood. This could be a reference to the resurrection of Jesus.
[Cueball and Danish are taking a stroll.] Cueball: How was Christmas? Did you go to church?
Danish: Yup. We celebrated the birth of a child, then we ate of his flesh and blood.
[Silence from Cueball.]
Danish: Seriously hope we got the right child this time.