Mystical Space Typhoon is a Trap Card that negates the activation of a Spell/Trap card, and destroys it if it does.
Spiritualism is a Spell Card that Special Summons a Level 4 or lower monster from your Graveyard to your field.
Therefore, if Mystical Space Typhoon is activated in response to Spiritualism's activation, it will negate Spiritualism and destroy it. This will prevent Spiritualism from summoning a monster from the Graveyard.
However, Spiritualism is not the only way to summon monsters from the Graveyard. There are other Spell/Trap cards and monster effects that can achieve the same result. So, while Mystical Space Typhoon can prevent Spiritualism from activating, it cannot prevent other methods of summoning monsters from the Graveyard.
In short, Mystical Space Typhoon can prevent Spiritualism from activating and summoning a monster from the Graveyard, but it cannot completely stop the activation of Spiritualism as a concept.