Allah commands His Messenger to say to the idoators:

﴿إِنَّمَآ يُوحَى إِلَىَّ أَنَّمَآ إِلَـهُكُمْ إِلَـهٌ وَحِدٌ فَهَلْ أَنتُمْ مُّسْلِمُونَ﴾

("It is revealed to me that your God is only one God. Will you then be Muslims'') meaning, will you then follow that and submit to it

﴿فَإِن تَوَلَّوْاْ﴾

(But if they turn away) means, if they ignore that to which you call them.

﴿فَقُلْ ءَاذَنتُكُمْ عَلَى سَوَآءٍ﴾

(say: "I give you a notice to be known to us all alike...'') meaning, `I declare that I am in a state of war with you as you are in a state of war with me. I have nothing to do with you just as you have nothing to do with me.' This is like the Ayah:

﴿وَإِن كَذَّبُوكَ فَقُل لِّى عَمَلِى وَلَكُمْ عَمَلُكُمْ أَنتُمْ بَرِيئُونَ مِمَّآ أَعْمَلُ وَأَنَاْ بَرِىءٌ مِّمَّا تَعْمَلُونَ ﴾

(And if they belie you, say: "For me are my deeds and for you are your deeds! You are innocent of what I do, and I am innocent of what you do!'') ﴿10:41﴾

﴿وَإِمَّا تَخَافَنَّ مِن قَوْمٍ خِيَانَةً فَانبِذْ إِلَيْهِمْ عَلَى سَوَآءٍ﴾

(If you fear treachery from any people, throw back (their covenant) to them (so as to be) on equal terms (that there will be no more covenant between you and them)) ﴿8:58﴾ which means: so that both you and they will know that the treaty is null and void. Similarly, Allah says here:

﴿فَإِن تَوَلَّوْاْ فَقُلْ ءَاذَنتُكُمْ عَلَى سَوَآءٍ﴾

(But if they turn away say: "I give you a notice to be known to us all alike...'') meaning, `I have already informed you that I have nothing to do with you and you have nothing to do with me.'