Yes ofcourse, we know of other existing dimensions, we just cant access it.There might be dimensions beyond what string theory states as well, but no one knows what they are, what is string theory suggests is the existence of a world beyond our own.Its just like asking a flatlander about our world.I think you need to get your arguments in a bit better order before I can engage with you any more.
Why did you appeal to string theory to show that there was things beyond materialism ? I presume you realise String Theory is a scientific theory?