The Holy scroll was as powerful as the Wish scroll.
Although Major Holy couldn't compare with the Shackles of Order set up by God Lance, the Order power contained within was very extraordinary.
The most important part was that Holy could repel evil chaotic lifeforms from entering the Sanctuary.
Marvin knew that with the current circumstances in White River Valley, a common Sanctuary wouldn't be as good.
After being the first to ignite the Source of Fire's Order, White River Valley was bound to be a thorn in many people's eyes.
Although an ordinary Sanctuary could protect those inside and resist the Wizard Monsters, it would be unable to repel them and other monsters.
But a Holy Sanctuary could.
Two of the three scrolls were used at once. It would be wrong to say that Marvin didn't feel any regret. But Pearl Island still had many resources, so it wasn't quite so bad.