AL 'ANKABUUT — Ayat 46
وَلَا تُجَادِلُوا أَهْلَ الْكِتَابِ إِلَّا بِالَّتِي هِيَ أَحْسَنُ إِلَّا الَّذِينَ ظَلَمُوا مِنْهُمْ وَقُولُوا آمَنَّا بِالَّذِي أُنزِلَ إِلَيْنَا وَأُنزِلَ إِلَيْكُمْ وَإِلَهُنَا وَإِلَهُكُمْ وَاحِدٌ وَنَحْنُ لَهُ مُسْلِمُونَ
And do not argue with the People of the Scripture except in a way that is best, except for those who commit injustice among them, and say, "We believe in that which has been revealed to us and revealed to you. And our God and your God is one; and we are Muslims [in submission] to Him."
Tafsir Ibnu Katsir
وَلاَ تُجَـدِلُواْ أَهْلَ الْكِتَـبِ إِلاَّ بِالَّتِى هِىَ أَحْسَنُ إِلاَّ الَّذِينَ ظَلَمُواْ مِنْهُمْ وَقُولُواْ ءَامَنَّا بِالَّذِى أُنزِلَ إِلَيْنَا وَأُنزِلَ إِلَيْكُمْ وَإِلَـهُنَا وَإِلَـهُكُمْ وَاحِدٌ وَنَحْنُ لَهُ مُسْلِمُونَ
46. And argue not with the People of the Scripture, except with that which is better -- except with such of them as do wrong; and say (to them): â€We believe in that which has been revealed to us and revealed to you; our God and your God is One, and to Him we have submitted.'' What is meant here is that anyone who wants to find out about religion from them should argue with them in a manner that is better, as this will be more effective. Allah says: