When a descendant of Cain commits murder, the statue of Cain becomes alive to exact revenge, and the killer is…A child!

You have me with bringing in "Cain" but the rest makes me question. My first response was aren't we all children of Cain (within the scope of that story)? Cain, Able, and possibly Seth were the children of Adam and Eve. No children are mentioned for any of them, but only Cain has any mention of a wife and going off to live life (according to what I just looked up, forgive me if I'm wrong). Your story might address this, but here in the logline it makes me scratch my head. Second thing you had me with is the statue coming to life. However, and this might just be me, the fact the child is the killer doesn't grab me the way it clearly is intended. I'm neutral on it. If I had this logline in front of me and the synopsis, I would read the synopsis, but I might not ask for one if I just got the logline. I don't know what I need, cause I'm still trying to learn logline writing, but I know I need something more to fully nab me. Sorry I can't be more helpful and say "it needs this!" Good luck!

...and one last point -- I think your 'hook' is misplaced -- the emphasis is on the fact that the killer is a child -- I'd see it more that a freakin statue comes alive to seek justice (or revenge, or what-have-you...)

It also reminds me of the Creepshow 2 story 'Old Chief Wood'nhead' where an old wooden Indian statue comes alive to kill an egotistical Indian criminal who kills the owner of the store the statue stands in...

...and wouldn't it make more sense, for a statue of Cain to become animated to enact revenge, if the VICTIM was a decedent of Cain's..? I'm not sure if 'revenge' is the right term to use when someone (or something) is righting a wrong, particularly in this scenario that seems about upholding the family name etc...-- it seems more like the Cain statue is seeking to PUNISH his decedent..? A fine distinction, sure, but something worth considering...

This just might be a personal taste thing, but I think you could watch the use of ellipses... Just a bit ... much...?...

True, but in my story, there's a gene, a part of the DNA, that's specific, like a calling card to wake the statue.

Wouldn't cain possibly have something close to 100 million living descendants? He would of been responsiable for Billions of deaths along the years.