User blog comment:B214/Volume 23 discussion blog/@comment-77.188.210.226-20170509230841/@comment-125.160.234.211-20170510192403

I think what prevents Gods from being able to be reincarnated is their divinity as Balor implied in Vol 16. Issei, although has both Ophis's power and GR's flesh, does not mean that Issei automatically has divinity. The Evil Pieces might be able to detect one's divinity directly but it might not be able to detect a dormant one, since Issei's ophis power stil lies dormant inside his body thus he was able to be reincarnated in Vol 12.