"And had it not been for the favor of my Lord," meaning: Islam, "I would have been among the brought [to punishment]," with you in the Fire.
﴿وَلَوْلَا نعْمَة رَبِّي﴾ يَعْنِي: الْإِسْلَام ﴿لَكُنْتُ مِنَ الْمُحْضَرِينَ﴾ مَعَك فِي النَّار