Those who have received “a spirit of adoption as sons ” are God’s spirit - begotten children.
وَرُوحُ ٱللهِ يَشْهَدُ مَعَ رُوحِهِمْ ،‏ فَيَعْلَمُونَ يَقِينًا أَنَّهُمْ أَوْلَادُ يَهْوَهَ ٱلْمَمْسُوحُونَ .‏