The story of Frankenstein also portrays man's Promethean attempt to mimic God, to play God through the act of creating life (the novel's subtitle itself is "The Modern Prometheus"!). Here, Frankenstein's side wound (which resembles the side wound of Christ) symbolizes the state of being a counterfeit Son of God. It is more subversive & inverted, than genuinely biblical, to juxtapose the symbolism of Christ (and other biblical symbols/motifs) with a creature brought into life through Promethean & artificial means like Frankenstein.
Moreover, since Frankenstein is the first literary & philosophical precursor of transhumanism, to juxtapose the symbolism of Christ within it ends up conveying the notion of the Antichrist itself — a counterfeit, a parody, & an inverted reflection of Christ; and to link this Antichristic character closely with the field of transhumanism.