Does Silence protect you from Blasphemy? Source, please.

[Deophaun]

Aside from Silence and being Evil I don't know of any defense against Blasphemy.

Spellblade.
Being able to hit a Bluff DC of 70.

[Renen]

The worst part isnt the DM not knowing the rules, its the DM not admitting he is wrong when shown proof.

[Honest Tiefling]

The worst part isnt the DM not knowing the rules, its the DM not admitting he is wrong when shown proof.

I don't like it...But I'm willing to bet everyone's done it at least once in their lives as well.

[ZamielVanWeber]

Spellblade.
Being able to hit a Bluff DC of 70.

One of those seems relevant to the average character. I also forgot you can try to counter the Blasphemy, for what it is worth.

[nedz]

Aside from Silence and being Evil I don't know of any defense against Blasphemy.

Aligned Planar Terrain Mastery — Horizon Walker 6+

[Forrestfire]

Spellblade.
Being able to hit a Bluff DC of 70.

Spellblades only work on targeted spells.

[Riculf]

I'd rule that the casting of the spell is "Sonic" (calling down your God's wrath on the impure, etc). As long as the God in question can "hear" the call, the spell works.

The effects of the spell have no sonic component as they are just the power of the God working through their intermediary (the caster). This would affect everyone in range regardless of silence/line of sight/etc.

[kellbyb]

I'd rule that the casting of the spell is "Sonic" (calling down your God's wrath on the impure, etc). As long as the God in question can "hear" the call, the spell works.

The effects of the spell have no sonic component as they are just the power of the God working through their intermediary (the caster). This would affect everyone in range regardless of silence/line of sight/etc.

Under that reasoning, aren't all spells with a verbal component "sonic"?

[Chronos]

The spell requiring that "your god hear you" or whatever would just be it having a verbal component. Which most spells do. The effect of the spell, though, is sonic, as evidenced by the [sonic] tag. You could even modify Blasphemy with the Silent Spell metamagic, which would have the effect that the caster wouldn't need to utter a thing, but would still magically produce the sound of an unholy word.

Incidentally, Word of Chaos and Holy Word both do require that the victims be able to hear them, while Blasphemy and Dictum do not. I'm not sure what the reason is for this asymmetry, which means that a deaf Lawful Evil character is immune to all four.

Oh, and all four of these spells also allow spell resistance, so that's another possible defense.

[Khedrac]

It's also worth noting that a number of later sonic effects (spells and creature abilities) specify that silence "merely" gives a bonus on the saving throw (usually +10 to +20 iirc). Personally I think this would be a good change to make to Blasphemy etc., but it is definitely a change. There is also an argument that the banishment effect will not be stopped by Silence, but that is a separate discussion.

As for ways to counter the Blasphemy, it also means that bardic countersong should work, but that would required a readied action or a bard pre-singing against Blasphemy just in case.

[ZamielVanWeber]

Blasphemy doesn't normally allow for a save; that is what makes it so potent.

[Chronos]

Quoth Khedrac:

It's also worth noting that a number of later sonic effects (spells and creature abilities) specify that silence "merely" gives a bonus on the saving throw (usually +10 to +20 iirc).

Examples? I don't think I've ever encountered this.

[Khedrac]

Examples? I don't think I've ever encountered this.

I may be semi-wrong on this one. I know we encountered at least one effect like this whilst playing the Savage Tide adventure path (I think) from Dungeon, but that's not WotC. I thought I had seen such stats written down somewhere, but since I do not recall where I am probably misremembering.

[Sewercop]

I'd rule that the casting of the spell is "Sonic" (calling down your God's wrath on the impure, etc). As long as the God in question can "hear" the call, the spell works.

The effects of the spell have no sonic component as they are just the power of the God working through their intermediary (the caster). This would affect everyone in range regardless of silence/line of sight/etc.

And here we might have the defending gm .....

[Deophaun]

I'd rule that the casting of the spell is "Sonic" (calling down your God's wrath on the impure, etc). As long as the God in question can "hear" the call, the spell works.

This is ableist discrimination against deaf gods.

[dascarletm]

I'd rule that the casting of the spell is "Sonic" (calling down your God's wrath on the impure, etc). As long as the God in question can "hear" the call, the spell works.

The effects of the spell have no sonic component as they are just the power of the God working through their intermediary (the caster). This would affect everyone in range regardless of silence/line of sight/etc.

Naw, The verbal component is the god hearing the request. The sonic part is the diety being all like:

evil caster gal: "EVIL GOD! Make these goodies stop harshing my mellow!"
EVIL GOD: "Hey you good... peeps stop being so good and stuff. You should like stop living."
-10HD good guy: "Oh that makes sense. Bleah!" *Dies*
-5HD good person: "ohmygawsh that's skary! Im stand here without mooobing nowz."
-1HD good dude: "EVIL GOD? uuuhhhggg arguing with you is sooo tiring..."
sameHD good friend: "Huh? what? ah! that's EVIL GOD... oh! right the fight my bad bros!"
moreHD good bro: "Pshh, yeah right I'm not doing that!"

So as you can see by my astute analysis this could not work in an area of silence.

[Lord of Shadows]

Since Blasphemy didn't exist until 3.x, and is a direct descendant of Unholy Word, it should work the same as Holy Word. Unfortunately, Holy Word is worded in a way that Blasphemy is not.

Holy Word: "Any nongood creature within the area that hears the holy word suffers the following ill effects."

Blasphemy: "Any nonevil creature within the area of a blasphemy spell suffers the following ill effects."

However, the secondary effect of both is worded exactly the same:

"This effect takes place regardless of whether the creatures hear the holy word."

"This effect takes place regardless of whether the creatures hear the blasphemy."

There should probably be a bit of Errata done here... Since there is No Save, preventing Silence as a defense against Blasphemy seems to make it more powerful than a 7th level spell. It certainly makes it more powerful than Holy Word, which should not normally be the case if they are intended to be opposites. Unless Blasphemy was intended by the designers to be more powerful than Holy Word for some reason.

However, in this case, it seems like the DM/GM is being bull-headed and stubborn, which can have many causes. Show your DM this thread, make him/her squirm in their seat.