The question seems somewhat ambiguous to me, but maybe can give some hints ... Gold Willing ...
First, Islam is and was and has always been the only religion from God (إِنَّ الدِّينَ عِنْدَ اللَّهِ الْإِسْلَامُ meaning "The Religion before Allah is Islam (submission to His Will)"), and Jesus' religion was no different ever, as Imam Sadiq PBUH has stated. When he PBUH was asked whether Jesus PBUH and his companions were Muslims or not, he answered yes, as Allah has already stated in Quran
فَلَمَّا أَحَسَّ عِيسَيٰ مِنْهُمُ الْكُفْرَ قَالَ مَنْ أَنْصَارِي
إِلَي اللَّهِ قَالَ الْحَوَارِيُّونَ نَحْنُ أَنْصَارُ اللَّهِ آمَنَّا
بِاللَّهِ وَ اشْهَدْ بِأَنَّا مُسْلِمُونَ
When Jesus found Unbelief on their part He said: 'Who will be My
helpers to (the work of) Allah?' Said the disciples: 'We are Allah's
helpers: We believe in Allah, and do thou bear witness that we are
Muslims.' [3:52]
Indeed there are Ahadeeth counting the worst wrongdoers of the history, among which two persons being of interest here, one is the person who made the followers of Moses PBUH Jew, and the other being the person who made the followers of Jesus PBUH Christian, which I guess he is Paul, the one who claimed God in a flesh, and Jesus PBUH not being a human.
But now why Jesus PBUH was not given this form of Islam and Quran that the prophet Muhammad PBUHH was given? There are perhaps several reasons for that, the followings being two possible examples:
First: Quran being in Arabic is not only because Arabic was the language used where it was revealed, but because Arabic is the language of creation, and it is "بِلِسَانٍ عَرَبِيٍّ مُبِينٍ", that is, in a clear and perspicuous Arabic language, every other language being lame to some extent when compared to Arabic if is used in its ultimate capacity. In Ahadeeth there are several remarks about this issue.
Second: while Jesus PBUH is considered in Ahadeeth to be one of the most knowledged prophets of Allah, but compared to knowledge of the holy prophet PBUH and his household PBUT his knowledge was a bit, as for example he has stated to his people that he will make clear some (but not all) of what they dispute:
لِأُبَيِّنَ لَكُمْ بَعْضَ الَّذِي تَخْتَلِفُونَ فِيهِ
in order to make clear to you some of the (points) on
which ye dispute
while to holy prophet PBUHH it was stated that
وَ يَوْمَ نَبْعَثُ فِي كُلِّ أُمَّةٍ شَهِيدًا عَلَيْهِمْ مِنْ
أَنْفُسِهِمْ وَ جِئْنَا بِكَ شَهِيدًا عَلَيٰ هَؤُلَاءِ وَ نَزَّلْنَا
عَلَيْكَ الْكِتَابَ تِبْيَانًا لِكُلِّ شَيْءٍ
One day We shall raise from all Peoples a witness over them, from
amongst themselves, and We shall bring thee as a witness over them,
and We have sent down to thee the Book explaining all things
and this is one reason for Why this last form of Islam is adequate for humanity for ever and the messengerhood is over, even when Jesus PBUH is returned to the Earth (and also John the Baptist PBUH, and all other martyred prophet of Allah PBUH, like Zachariah PBUH and etc.) at the end of times, there is no message left to convey anymore:
وَ مَا أَرْسَلْنَاكَ إِلَّا كَافَّةً لِلنَّاسِ
And We have not sent you except comprehensively and universal to
mankind
