Allah said,

﴿وَقَفَّيْنَا﴾

(and We sent...) meaning, We sent

﴿عَلَى ءَاثَـرِهِمْ﴾

(in their footsteps) meaning the Prophets of the Children of Israel,

﴿بِعَيسَى ابْنِ مَرْيَمَ مُصَدِّقاً لِّمَا بَيْنَ يَدَيْهِ مِنَ التَوْرَاةِ﴾

(`Isa, son of Maryam, confirming the Tawrah that had come before him,) meaning, he believed in it and ruled by it.

﴿وَءَاتَيْنَـهُ الإِنجِيلَ فِيهِ هُدًى وَنُورٌ﴾

(and We gave him the Injil, in which was guidance and light) a guidance that directs to the truth and a light that removes the doubts and solves disputes,

﴿وَمُصَدِّقاً لِّمَا بَيْنَ يَدَيْهِ مِنَ التَّوْرَاةِ﴾

(and confirmation of the Tawrah that had come before it,) meaning, he adhered to the Tawrah, except for the few instances that clarified the truth where the Children of Israel differed. Allah states in another Ayah that `Isa said to the Children of Israel,

﴿وَلاٌّحِلَّ لَكُم بَعْضَ الَّذِي حُرِّمَ عَلَيْكُمْ﴾

(. ..and to make lawful to you part of what was forbidden to you.) So the scholars say that the Injil abrogated some of the rulings of the Tawrah. Allah's statement,

﴿وَهُدًى وَمَوْعِظَةٌ لِّلْمُتَّقِينَ﴾

(a guidance and an admonition for those who have Taqwa.) means, We made the Injil guidance and an admonition that prohibits committing sins and errors, for those who have Taqwa of Allah and fear His warning and torment. Allah said next,

﴿وَلْيَحْكُمْ أَهْلُ الإِنجِيلِ بِمَآ أَنزَلَ اللَّهُ فِيهِ﴾

(Let the people of the Injil judge by what Allah has revealed therein.) meaning, so that He judges the people of the Injil by it in their time. Or, the Ayah means, so that they believe in all that is in it and adhere to all its commands, including the good news about the coming of Muhammad and the command to believe in and follow him when he is sent. Allah said in other Ayat,

﴿قُلْ يَـأَهْلَ الْكِتَـبِ لَسْتُمْ عَلَى شَىْءٍ حَتَّى تُقِيمُواْ التَّوْرَاةَ وَالإِنجِيلَ وَمَآ أُنزِلَ إِلَيْكُمْ مِّن رَّبِّكُمْ﴾

(Say "O People of the Scripture! You have nothing (guidance) until you act according to the Tawrah, the Injil, and what has been sent down to you from your Lord.'') and,

﴿الَّذِينَ يَتَّبِعُونَ الرَّسُولَ النَّبِىَّ الأُمِّىَّ الَّذِى يَجِدُونَهُ مَكْتُوبًا عِندَهُمْ فِى التَّوْرَاةِ﴾

(Those who follow the Messenger, the Prophet who can neither read nor write whom they find written with them in the Tawrah...) until,

﴿الْمُفْلِحُونَ﴾

(...successful.) Here, Allah said,

﴿وَمَن لَّمْ يَحْكُم بِمَآ أَنزَلَ اللَّهُ فَأُوْلَـئِكَ هُمُ الْفَـسِقُونَ﴾

(And whosoever does not judge by what Allah has revealed, such are the rebellious.) meaning, the rebellious and disobedient of Allah who prefer falsehood and abandon truth. We mentioned before that this Ayah was revealed about the Christians, and this is evident from the context of the Ayah.

﴿وَأَنزَلْنَآ إِلَيْكَ الْكِتَـبَ بِالْحَقِّ مُصَدِّقاً لِّمَا بَيْنَ يَدَيْهِ مِنَ الْكِتَـبِ وَمُهَيْمِناً عَلَيْهِ فَاحْكُم بَيْنَهُم بِمَآ أَنزَلَ اللَّهُ وَلاَ تَتَّبِعْ أَهْوَآءَهُمْ عَمَّا جَآءَكَ مِنَ الْحَقِّ لِكُلٍّ جَعَلْنَا مِنكُمْ شِرْعَةً وَمِنْهَـجاً وَلَوْ شَآءَ اللَّهُ لَجَعَلَكُمْ أُمَّةً وَحِدَةً وَلَـكِن لِّيَبْلُوَكُمْ فِى مَآ ءَاتَـكُم فَاسْتَبِقُوا الخَيْرَاتِ إِلَى الله مَرْجِعُكُمْ جَمِيعاً فَيُنَبِّئُكُم بِمَا كُنتُمْ فِيهِ تَخْتَلِفُونَ - وَأَنِ احْكُم بَيْنَهُمْ بِمَآ أَنزَلَ اللَّهُ وَلاَ تَتَّبِعْ أَهْوَآءَهُمْ وَاحْذَرْهُمْ أَن يَفْتِنُوكَ عَن بَعْضِ مَآ أَنزَلَ اللَّهُ إِلَيْكَ فَإِن تَوَلَّوْاْ فَاعْلَمْ أَنَّمَا يُرِيدُ اللَّهُ أَن يُصِيبَهُم بِبَعْضِ ذُنُوبِهِمْ وَإِنَّ كَثِيراً مِّنَ النَّاسِ لَفَـسِقُونَ - أَفَحُكْمَ الْجَـهِلِيَّةِ يَبْغُونَ وَمَنْ أَحْسَنُ مِنَ اللَّهِ حُكْماً لِّقَوْمٍ يُوقِنُونَ ﴾

(48. And We have sent down to you the Book (this Qur'an) in truth, confirming the Scripture that came before it and Muhayminan over it (old Scriptures). So judge between them by what Allah has revealed, and follow not their vain desires, diverging away from the truth that has come to you. To each among you, We have prescribed a law and a clear way. If Allah willed, He would have made you one nation, but that (He) may test you in what He has given you; so compete in good deeds. The return of you (all) is to Allah; then He will inform you about that in which you used to differ.) (49. And so judge between them by what Allah has revealed and follow not their vain desires, but beware of them lest they turn you far away from some of that which Allah has sent down to you. And if they turn away, then know that Allah's will is to punish them for some sins of theirs. And truly, most men are rebellious. (50. Do they then seek the judgement of (the days of) ignorance And who is better in judgement than Allah for a people who have firm faith.)