In verse 55 of Aal-i Imran, God states that:

Question:
In verse 55 of Aal-i Imran, God states that: “…and I shall set those who follow you [Jesus (a)] above the faithless until the Day of Resurrection.” If this is the case and the followers of Prophet Jesus (a) are indeed superior amongst all the disbelievers, then why should we follow the religion of Prophet Muhammad (s)? Instead, we should follow the religion of Prophet Jesus (a) so that on the Day of Resurrection, we may be considered superior amongst all the disbelievers.

Answer:
Various responses and views have been presented regarding this particular verse. We will use this as an opportunity to discuss several of them.
1 - What is meant by the followers of Prophet Jesus (a) is in fact the followers of Prophet Muhammad (s). Three arguments substantiate this claim:
a) Chronologically speaking, the religion of Prophet Muhammad (s) and his followers succeeds that of Prophet Jesus (a).
b) Our Prophet, the Prophet Muhammad (s), re-affirmed the religion of Prophet Jesus (a) and his divine book. It can be said that if a person affirms and individual and their message as being true, they have in reality followed the other.
c) The law brought by the Prophet Muhammad (s) is in unity with the message of monotheism preached by the Prophets who preceded him. This is a significant point because monotheism is the foundation of religion.
2 - What is meant by the phrase “following” in the aforementioned verse refers to a following that is truthful and legitimate in essence. Meaning, this following should be in line with the will of God, the Almighty. Hence, when the Holy Qur’aan says “those who follow you,” it is in reality referring to the Christians who preceded Islam and the Muslims who followed Islam as their religion after its revelation.
3 - The mentioned verse is informing the Christians that God will elevate their status above that of the Jews. This interpretation is in accordance with the apparent meaning of the verse.
4 - This verse is addressing both Christians and Muslims. The message it wishes to convey is that the Jews are, until the Day of Resurrection, inferior to whoever that considers following Prophet Jesus (a) obligatory upon themselves. Note that this includes both Christians, who hold the message of Prophet Jesus (a) as the cornerstone of their faith, and Muslims, who hold the Prophet (a) in high esteem as one of the divinely inspired prophets of God.
However, the question remains as to why Muslims are not considered amongst those who disbelieved in the prophethood of Prophet Jesus (a). It should be noted that the term ‘disbeliever’ here is referring to one who denies the truth. Meaning, the Jews who deny the legitimacy of Jesus’ (a) prophethood. However, not only do Muslims affirm the validity of the prophethood of Prophet Jesus (a), rather, they are his true followers and the followers of his successor, the Prophet Muhammad (s).
Muslims consider Prophet Jesus (a) as being one of the greatest prophets in history and the messenger of a divine book and law. Furthermore, they consider him as the third of the Ulu al-‘Azm. Therefore, when God states that “…I shall set those who follow you [Jesus (a)] above the faithless until the Day of Resurrection,” there is no possibility whatsoever that He’s alluding to the Muslims because this statement doesn’t even apply to them.

Detailed Answer
To begin with, the translation and interpretation of verse 55 of Aal-i Imraan which you mentioned in your question is imprecise. In order to correctly respond to your question, we must first look at an accurate translation of that verse, followed by the necessary interpretation.
Below is the translation of verse 55 of Aal-I Imraan:
“…and I shall set those who follow you [Jesus (a)] above the faithless until the Day of Resurrection. Then to Me will be your return, whereat I will judge between you concerning that about which you used to differ.” [1]
In order to provide a precise response, a few matters must initially be clarified. By taking a look at the discussions provided below and critically assessing the mentioned verse, we will reach a favorable conclusion.
Various responses and views have been presented regarding this particular verse. We will use this as an opportunity to discuss several of them.
1- What is meant by the followers of Prophet Jesus (a) is in fact the followers of Prophet Muhmmad (s). Three arguments substantiate this claim:
a) Chronologically speaking, the religion of Prophet Muhammad (s) and his followers succeeds that of Prophet Jesus (a). When it is said that one succeeds the other, it means that there was an individual who was followed by another after him. It’s important to note that the coming of one does not contradict the coming of another.
b) Our Prophet, the Prophet Muhammad (s), re-affirmed the religion of Prophet Jesus (a) and his divine book. It can be said that if a person affirms and individual and their message as being true, they have in reality followed the other.
c) The law brought by the Prophet Muhammad (s) is in unity with the message of monotheism preached by the Prophets who preceded him. This is a significant point because monotheism is the foundation of religion. Thus, the Prophet Muhammad (s) was in fact among the followers of Prophet Jesus (a) and a believer in the message he preached. [2]
2- What is meant by the phrase “follow” in the aforementioned verse refers to a following that is truthful and legitimate in essence. Meaning, this following should be in line with the will of God, the Almighty. Hence, when the Holy Qur’aan says “those who follow you,” it is in reality referring to the Christians, who preceded Islam, and the Muslims who followed Islam as their religion after its revelation. Muslims are considered within this fold because a true adherent of Islam is one who follows the truthful messages of God, which includes the divine message of Jesus (a).[3]
‘AllaamahTabaatabaa’i has attributed this view to some interpreters and criticizes such a claim. [4]
3- The mentioned verse declares that God, the Almighty, deems the Christians[5]superior to the Jews whose ancestors disbelieved in the prophethood of Jesus (a) and plotted against him. It intends to inform that the divine punishment of God shall descend upon the Jews with severity. [6]
This interpretation, which is in line with the apparent meaning of the verse, is amongst those miraculous Qur’aanic verses which foretell significant incidents to come. Its message is clearly stated: the followers of Prophet Jesus (a) will be forever superior to the Jews who opposed this divine Prophet.
In present times, this reality can be seen before us. Without the support of the Christians, the Jews and Zionists of today cannot pursue their political and social agendas for even a day. [7] In other words, they have become completely self-reliant upon the nation which they once fought against.
Therefore, from this perspective, it’s understood that the followers of Prophet Jesus (a) are the Christians, who throughout any given time and place, have triumphed over the Jews and proven them inferior. It is for this reason that the Christians have taken power and authority from the Jews. Self-evident examples of this can be seen throughout history in places such as Europe and Rome. In addition, the Christians have become more likeable in the eyes of society than the Jews and shall hold this favorable position until the Day of Resurrection.[8]
4- When the Holy Qur’aan states “الَّذِينَ اتَّبَعُوکَ” (transliterated: alladhinaattaba‘uk), meaning “those who follow you,” the intended followers include both the Christians and Muslims together. The message it wishes to convey is that the Jews are, until the Day of Resurrection, inferior to whoever that considers following Prophet Jesus (a) obligatory upon themselves.[9] Note that this includes both Christians, who hold the message of Prophet Jesus (a) as the cornerstone of their faith, and Muslims, who believe hold the Prophet (a) in high esteem as one of the divinely inspired prophets of God.
However, the question remains as to why Muslims are not considered amongst those who disbelieved in the prophethood of Prophet Jesus (a).
The word ‘faithless’ (kaafir) in this context means one who denies. [10] Not only do Muslims affirm the legitimacy of the Prophet Jesus (a) and his message, but consider him one of the greatest prophets in history and the messenger of a divine book and jurisprudence. Furthermore, they consider him as the third of the Ulul al-‘Azm. God, the Almighty, states in His Holy Qur’aan: “He said, ‘Indeed I am a servant of Allah! He has given me the Book and made me a prophet.” [11]
History shows no account of Muslims denying Prophet Jesus (a) or his message. In fact, those who denied his prophethood and seemingly killed him were the Jews.
Therefore, when God states that “…I shall set those who follow you [Jesus (a)] above the faithless until the Day of Resurrection,” there is no possibility whatsoever that He’s alluding to the Muslims because this statement doesn’t even apply to them.
Consequently, the phrase “الَّذِينَ اتَّبَعُوکَ” (transliterated: alladhinaattaba‘uk), includes all the followers of Prophet Jesus (a) - to which both Muslims (based on the interpretation provided) and Christians are amongst. In addition, the correct translation of the verse is as follows: “…and I shall set those who follow you above the faithless until the Day of Resurrection. Then to Me will be your return, whereat I will judge between you concerning that about which you used to differ.”
In conclusion, it is necessary to mention the following note:
If a person is to choose one of two routes, the first being a path of truth followed by apparent defeat and the second, a path of falsehood followed by apparent victory, it is better that one choose the first route. This was the path that Imam Husayn (a) chose. Bearing this in mind, if the legitimacy of Islam as a divine faith becomes clear to us, it would be illogical for to adhere to a religion such as Christianity in hopes of becoming seemingly victorious (as the reasoning which you’ve provided alludes). The following verse of the Holy Qur’aan is one amongst many which attest to this fact: “Never will the Jews be pleased with you, nor the Christians, unless you followed their creed. Say, ‘Indeed it is the guidance of Allah which is the [true] guidance.’ And should you follow their desires after the knowledge that has come to you, you will not have against Allah any guardian nor any helper.” [12]

Refrence:

[1] Translated by Ali QuliQara'i
[2] Tabarsi, FadhlibnHusayn, Majma‘ al-Bayaan fi Tafsir al-Qur’aan , Multiple Translators, Volume 4, p. 94, Farahaani Publications, Tehran, First Edition, 1360.
[3] Tabaatabaa’i, Muhammad Husayn, Tafsir al-Mizaan, MusawiHamadani, Sayyid Muhammad Baaqir, Volume 3, p. 326, Volume 3,p.327, the Islamic Publication Office of Jaami‘eh-ye Mudarrisin of the Islamic Seminary of Qum, Qum, Fifth Edition, 1374.
[4] Tabaatabaa’i, Muhammad Husayn, Tafsir al-Mizaan, MusawiHamadani, Sayyid Muhammad Baaqir, Volume 3, pp. 328 and 329.
[5] Tabarsi, FadhlibnHusayn, Majma‘ al-Bayaan fi Tafsir al-Qur’aan , Multiple Translators, Volume 4, p. 94.
[6] Tabaatabaa’i, Muhammad Husayn, Tafsir al-Mizaan, MusawiHamadani, Sayyid Muhammad Baaqir, Volume 3,p.330.
[7] MakaarimShiraazi, Naasir, Tafsir-i Nemuneh, Volume 2, p. 570, Daar al-Kitaab al-Islaamiyyah, Tehran, First Edition, 1374.
[8] Tabarsi, FadhlibnHusayn, Majma‘ al-Bayaan fi Tafsir al-Qur’aan , Multiple Translators, Volume 4, p. 94.
[9] Tabaatabaa’i, Muhammad Husayn, Tafsir al-Mizaan, MusawiHamadani, Sayyid Muhammad Baaqir, Volume 3, p.330.
[10] Faraahidi, Khalil ibn Ahmad, Kitaab al-‘Ayn, Volume 5, p. 356, Second Edition, Hijrat Publications, Qum, 1410.
[11] The Holy Qur’aan, Chapter Maryam, Verse 30
[12] The Holy Qur’aan, Chapter Baqarah, Verse 120
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