Quote Originally Posted by Mirage
I believe Holy would have activated much earlier if Aeris hadn't died. If Aeris had lived, holy would have been able to nullify Meteor in time, but it seemed as if Meteor had reached the "point of no return" (if you want to put it that way) by the time it activated, that's why the lifestream had to help it.
I think the only reason why Holy activated so late was that Sephiroth was blocking it. Here's some dialogue from the game.

(In the Forgotten Capital, Cloud, Bugenhagen and others are watching a projection of the scene when Aeris died.)

CLOUD: "... It's glowing."
BUGENHAGEN: "Ho Ho Hooo!! It's pale green!!"
CLOUD: "... Aeris. Aeris has already prayed for Holy... After I gave the Black Materia to Sephiroth... Aeris's words came into my dreams... She said, she was the only one who could stop Sephiroth... And to do that, there was a secret here... That was Holy... That's why, she had the White Materia. Aeris knew about here... and what she had to do. Aeris has left us great hope. But, it cost her her life... her future... I'm sorry... Aeris. I should have figured this out sooner... You left us without saying a word... It was all so sudden, so I couldn't think... That's why it took so long for me to find out... But, Aeris... I understand now. Aeris... I'll do the rest."

CLOUD: "Thank you... Aeris. Aeris's voice has already reached the Planet. Just look at the glow of the White Materia. But... how about Holy? How come Holy isn't moving? Why?"
BUGENHAGEN: "Something's getting in its way."
CLOUD: "... Him... He's the only one that could do it... Sephiroth. Where are you?"