Overall meaning : Almighty Allah explains in these  the nature of the religion that people must practise to worship Him, stating that it is Islam, which, He stresses, is the only true religion acceptable to Him.
Then He indicates that the People of the Book only differed after evidence had been established against them through the sending of messengers and the revelation of scriptures, and that their differences and disagreements only arose from the transgressions and injustices they had committed.
Next, He points out the punishment He will mete out to those who deny His signs, stressing that He will repay them for their deeds, of which He keeps count.  Indeed, He is swift in reckoning and in calling to account.
Addressing His Messenger, may Allah bless him and grant him peace, Allah teaches him how to respond to their vain arguments, stating that if they resort to falsehood to argue with him concerning the truth that has come to him, he should say to them that he has sincerely surrendered his will to Allah, and so have those who follow him, and to ask the People of the Book and the idolaters, ‘Will you also submit yourselves to Allah and worship Him alone?’ If they surrender to Allah’s will and follow Islam, then they are on the right path. But if they turn away from the truth he is calling them to, then his only duty is to convey his message. Allah sees all His servants and knows full well who follows the right path and who has strayed from it. To Him they will all be returned, and He will judge them according to their deeds.