The Final Conflict was the concluding chapter in The Omen trilogy (well, it was until someone had the bright idea to flog a dead horse with Omen IV…)
I always found it a poor fit with the previous two movies, the basic premise being that the Devil’s son Damien is now a grown adult, intent on preventing the second coming of Christ by killing all male babies born in the UK on the predicted date. Showing a grown-up and malevolent Damien, whilst logical, just doesn’t capture the imagination in the same way as Omens I and II, in which death inevitably follows those who get in the way of a seemingly innocent child.
Sam Neill gives a decent effort as the anti-christ and there are a few well-handled graphic deaths (most notably when the American ambassador arranges to blow his own brains out when journalists enter his office). But the squad of monks armed with sacred knives sent to kill him (who all inevitably fail one-by-one) don’t really provide much in the way of opposition.
This is the UK quad poster and is for sale here.