On reading Christian literature, do you look away? Are you disgusted and angered? If Muslim and you look away, then you have the 'mark.' You are stained.

I know the Truth and then there is the Quran which I also know; but I have not been stained by it.

Are you so fearful of the truth and blinded by lies that you look away? Who can take away the stain of the Quran and its lies about Jesus? Jesus is the truth.