Ya ayyuha allatheena amanoo koonoo ansara Allahi kama qala AAeesa ibnu maryama (surah Saff: 14)

Tafseer Tafheem-ul-Quran by Syed Abu-al-A'la Maududi

(61:14) O you who have believed! Be helpers of Allah even as Jesus, son of Mary, had said to the disciples,' *19 "Who will be my helpers (in calling) towards Allah?" and the disciples had answered,"We are helpers of Allah. " *20 Then, some of the children of Israel believed and others disbelieved. So We aided the believers against their enemies, and they alone became triumphant. *21

Yaaa ayyuhal lazeena aamaanoo koonooo ansaaral laahi kamaa qaala `Eesab-nu-Maryama lil Hawaariyyeena man ansaareee ilal laah; qaalal Hawaariyyoona nahnu ansaa rul laahi fa aamanat taaa`ifatum mim Bannee Israaa`eela wa kafarat taaa`ifatun fa ayyadnal lazeena aammanoo `alaa `aduwwihim fa asbahoo zaahireen

*19) For the companions of the Prophet Jesus (peace be on him) the word `Disciples" generally has been used in the Bible, but later the term "apostle" became prevalent for them among the Christians, and in the sense that they were God's apostles, but in the sense that the Prophet Jesus used to send them to different parts of Palestine as his preachers. Among the Jews this word was already in use for those who were sent to collect subscriptions for the Temple. However, the Qur'anic term "hawari" is better than both the Christian terms. The essence of this word is hur, which means whiteness. The washerman is called hawari because he whitens clothes by washing them. A pure and un-adulterated thing is also called hawari . The flour from which bran has been sifted is known as huwwara. In this very meaning this word is used for a sincere friend and an unselfish supporter. Ibn Sayyidah says: "Anyone who exaggerates in helping another is his hawari." (Lisan al-'Arab).
*20) This is the last place in the Holy Qur'an where those who exert themselves in calling the people to Allah's Religion and to cause it to become dominant over disbelief, have been called helpers of Allah. Before this, this very theme has been expressed in Al-'Imran: 52, Al-Hajj: 40, Muhammad: 7, Al-Hadid25 and Al-Hashr: 8 above, and we have explained these verses in E.N. 50 of Al Imran, E.N. 84 of Al-Hajj, E.N. 12 of Muhammad, E.N. 47 of Al-Hadid.
Moreover, in E. N . 9 of Surah Muhammad also light has been thrown on an aspect of this question. In spite of this some people seem to have the confusion that when AIIah Almighty is All-Powerful, Self-Sufficient, and Independent of the help of all His creatures, how then can a man be a helper of Allah? To remove this confusion we shall further explain this point here.
In fact, these people have not been called helpers of AIIah for the reason that Allah, Lord of the worlds, (God forbid) stood in need of any help from some of His creatures, but because in the sphere of life in which Allah Himself has granted man freedom of belief and disbelief, obedience and disobedience, He does not will to make the people His believers and obedient servants by means of His power and might. Instead, He adopts the method of admonition and instruction to show them the right way through His Prophets and Books. The one who accepts this admonition and instruction willingly is a Mu'min, the one who submits practically to His Commands, is a Muslim and devout God-worshipper, the one who adopts an attitude of God-consciousness is a Muttaqi, the one who vies with others for good works is a Muhsin, and over and above this, the one who starts working for the reformation of the people by means of the same method of admonition and instruction and for establishing the system of Allah's obedience instead of disbelief and wickedncss, is declared by Allah as His own helper, as has been mentioned in clear words at several places in the verses cited above. If the object were to designate such people as helpers of Allah's Religion and not of AIIah, the words would have been ansar-u din Allah and not ansar-Allah, yansuruna din-Allah and not yansurun-Allah, intansuruna din-Allah and not in-iansurun-Allah. When in order to convey and express a theme; Allah has adopted one and the same style at several places, successively, it proves conclusively that the actual object is to designate these people as helpers of Allah. But this "helpfulness", God forbid, is not in the sense that these people fulfil some need of AIIah for which He requires their help, but it is in the sense that these people participate in the cause which Allah wills to accomplish through His Prophets and His Books instead of His great power and might.
*21) Those who disbelieved in Jesus Christ are the Jews, and those who believed in him are the Christians as well as the Muslims, and Allah granted both these domination over the disbelievers of Christ. This is meant to requires the Muslims that just as the believers of Christ have dominated over his disbelievers in the past, so will the believers of the Prophet Muhammad (upon whom be Allah's peace) prevail over his disbelivers.