Jesus tries to explain what the "Kingdom of God" is like in this teaching, He describes it this way -- 

"It's like a mustard seed, which, when sown upon the soil, though it is smaller than all the seeds that are upon the soil, yet when it's sown, grows up and becomes larger than all the garden plants and forms large branches; so that the birds of the air can nest under its shade." 

As I considered the meaning I saw the seed, which I take to be the word of God -- sown upon the soil, which is the earth --  growing up in the garden, which I think may represent the spiritual pursuits of humanity -- and from it's meager beginnings -- beginning with 12 disciples -- it extends it's branches and offers shade -- which I believe may be spiritual rest -- to all the birds of the sky; which again, I think may represent all spiritual pursuits. 

  I think Jesus saw all religions as containing a germ of truth, but incomplete. And in His kingdom, all are welcome and will find the completion and fulfillment in Him. I don't think Jesus was hostile or antagonistic towards other religions whatever they were, or even those who had no religion. His only harsh words were towards the hypocrite. I know that may seem overly generous to some, but I believe Jesus came to unite and not divide. As I read about how He ministered to the non-Jew, even those hostile to the Jews, I always see acceptance and invitation, not division.