if you read the first amendment in a historical vacuum then yes is forbids an establishment and does not explicitly speak about 'separation'. However if you read what almost all of the major 'founding father' figures were writing at the time, and what they said about it afterwards it is obvious that they intended to separate church and state affairs. Of the major 'founding fathers' that everyone hears about (Franklin, Jefferson, Washington, Paine, Madison, Adams, etc.) they were all secularists at the very least but many of them were outspoken Deists who were nothing if not hateful of organized religion both philosophically and as it relates to governance. Furthermore 'separation' is an arbitrary distinction from a lack of establishment, both of those words have different meanings depending on who is arguing at a given moment and those meanings always meld to fit whatever agenda they are pushing.