This line (tukh) does match sikh theology correctly,

"But I have forgotten all vain religions and know in my heart That the Creator is the only God".

the whole point of this tukh from what i can understand is that vain religions are those where theology and dogma have no sense and lead to a path of ritual and ignorance rather then spiritual development.

One thing you should know sikhi does accept those faiths that are good and do good we do not accept anyone who comes into this world and does bad or imposes bad on the world for we as sikhs are the protectors of the planet.

read tavprasaad swaiye (sravag sud) this will show you the way https://www.youtube.com/watch?v=NWUrwFPiQDI

and answer this question in a whole.