Duh. And yet, scripture itself is clear enough in any language to be able to discern its meaning.
I know what it says.
IT DOESN'T SAY that the Lamb was slain from the foundation of the world.
You're omitting the most important part, and that is causing your confusion.
Don't leave out the book that's being talked about IN THAT VERY VERSE IMMEDIATELY PRIOR TO THAT PHRASE!
All who dwell on the earth will worship him,
whose names have not been written in the Book of Life of the Lamb slain from the foundation of the world. - Revelation 13:8
http://www.biblegateway.com/passage/?search=Revelation13:8&version=NKJV
The title of the book is "The Book of Life."
It belongs to the Lamb who was slain.
Names have been written in it from the foundation of the world. Those people, whose names have not been written in the book from the foundation of the world, will worship the beast.
The beast that you saw was, and is not, and will ascend out of the bottomless pit and go to perdition. And those who dwell on the earth will marvel,
whose names are not written in the Book of Life from the foundation of the world, when they see the beast that was, and is not, and yet is. - Revelation 17:8
http://www.biblegateway.com/passage/?search=Revelation17:8&version=NKJV
The title of the book is "the Book of Life."
Names have been written in the book from the foundation of the world, and those who have not had their name written in it will marvel at the beast.
And
anyone not found written in the Book of Life was cast into the lake of fire. - Revelation 20:15
http://www.biblegateway.com/passage/?search=Revelation20:15&version=NKJV
The title of the book: "The Book of Life."
Anyone who doesn't have their name in the book is cast into the lake of fire.
But there shall by no means enter it anything that defiles, or causes an abomination or a lie, but
only those who are written in the Lamb’s Book of Life. - Revelation 21:27
http://www.biblegateway.com/passage/?search=Revelation21:27&version=NKJV
Again, the book, which belongs to the Lamb, is called the "Book of Life."
Names were written in it, and those whose names were written in it shall enter.
Do you get it yet?
Here's one more!
And I urge you also, true companion, help these women who labored with me in the gospel, with Clement also, and the rest of my fellow workers,
whose names are in the Book of Life. - Philippians 4:3
http://www.biblegateway.com/passage/?search=Philippians4:3&version=NKJV
The title of the book is "The Book of Life."
Paul's fellow workers' names were written in it.
In short:
The "Book of Life" contains names written in it. Those names have been added to the book
since creation. "Since creation" is what the phrase "from the foundation of the world" means. The book belongs to the Lamb, who was slain for the sins of the world.
Scripture is NOT saying that Christ was being crucified since the beginning of creation, which is what it would mean if YOUR position were correct.
Clearly, that is not the case. CHRIST WAS NOT BEING SLAIN FROM THE FOUNDATION OF THE WORLD.