Overall meaning : Almighty Allah emphatically affirms that the Christians are surely unbelievers for making the assertion that Allah is the Messiah, Jesus son of Mary, peace be upon him. He points out that the Messiah himself said to the Children of Israel: Worship none but Allah, my Lord and your Lord. Allah will exclude anyone who worships others with Him from Paradise, and his abode will be the Fire. Those who wrong themselves by worshipping others besides Allah will have no helpers to protect and save them from Allah’s punishment.
He also emphatically declares that those Christians who deify Jesus and his mother and take them as gods besides Allah, thus making Allah the third in a trinity (as well as those who hold that He is three persons in one: The Father, the Son and the Holy Ghost) —Exalted is He above what they claim—are certainly unbelievers for making such a claim. He affirms that none is really deserving of worship except He and points out the terrible consequences these misguided people will suffer as a result of making such a claim, stating that if they do not desist from making such a blasphemous contention and forging such a monstrous lie, a grievous punishment will surely befall those of them who persist in their unbelief by clinging to such assertion. After giving the unbelievers such a stern warning, the Almighty throws open the door of His mercy wide open before them by making them desirous to embrace faith and exhorting them to turn to Him in penitence and seek His forgiveness, assuring them that He is All-Forgiving, All-Merciful.
The Almighty then reveals the absolute truth about the Messiah and his mother and proves beyond any shadow of doubt that the truth is not what these unbelieving Christians claim it to be. Jesus, He clearly explains, was the son of Mary and was no more than a messenger, just like all the other messengers He had send before him, and his mother was a virtuous and truthful woman, both of them ate food to satisfy their needs like all other mortals. See, then, Muhammad, He tells His Prophet, how We offer them clear, conclusive evidence, and see how   they cling to their misguided ideas and turn away from the truth despite such clear proofs. He also instructs him to say to them, by way of reproof and exhortation, ‘Would you worship besides Allah what can neither harm you nor profit you when Allah alone is All-Hearing, All-Knowing?!’
Almighty Allah further instructs His Prophet to warn them against going to extremes and transgressing the bounds of truth in their religion, and to caution them against following the whims of their ignorant leaders and monks who have gone astray before them, have mislead many others and have themselves deviated considerably from the right path.