One of the question asked is can a Christian enter Jannah today?

 One of the question asked is can a Christian enter Jannah today?

Alhamdulillah, it is clear from Quran and hadiths that any christian who dies believing Jesus is God or son of God and do not believe in prophet Muhammad Peace be Upon Him will enter hellfire.

Allah says,

Al-Ma'idah 5:17

They have certainly disbelieved who say that Allāh is Christ, the son of Mary. Say, "Then who could prevent Allāh at all if He had intended to destroy Christ, the son of Mary, or his mother or everyone on the earth?" And to Allāh belongs the dominion of the heavens and the earth and whatever is between them. He creates what He wills, and Allāh is over all things competent.

Allah says,

Al-Ma'idah 5:72

لَقَدۡ كَفَرَ ٱلَّذِينَ قَالُوٓاْ إِنَّ ٱللَّهَ هُوَ ٱلۡمَسِيحُ ٱبۡنُ مَرۡيَمَۖ وَقَالَ ٱلۡمَسِيحُ يَٰبَنِيٓ إِسۡرَٰٓءِيلَ ٱعۡبُدُواْ ٱللَّهَ رَبِّي وَرَبَّكُمۡۖ إِنَّهُۥ مَن يُشۡرِكۡ بِٱللَّهِ فَقَدۡ حَرَّمَ ٱللَّهُ عَلَيۡهِ ٱلۡجَنَّةَ وَمَأۡوَىٰهُ ٱلنَّارُۖ وَمَا لِلظَّٰلِمِينَ مِنۡ أَنصَارࣲ

They have certainly disbelieved who say, "Allāh is the Messiah, the son of Mary" while the Messiah has said, "O Children of Israel, worship Allāh, my Lord and your Lord." Indeed, he who associates others with Allāh - Allāh has forbidden him Paradise, and his refuge is the Fire. And there are not for the wrongdoers any helpers.

The Christians that will enter Jannah was the Christians who aided the Muslims when they made hijrah to Abysinia.

Allah says,

Al-Ma'idah 5:82

You will surely find the most intense of the people in animosity toward the believers [to be] the Jews and those who associate others with Allāh; and you will find the nearest of them in affection to the believers those who say, "We are Christians." That is because among them are priests and monks and because they are not arrogant.

Al-Ma'idah 5:83

And when they hear what has been revealed to the Messenger, you see their eyes overflowing with tears because of what they have recognized of the truth. They say, "Our Lord, we have believed, so register us among the witnesses.

Al-Ma'idah 5:84

And why should we not believe in Allāh and what has come to us of the truth? And we aspire that our Lord will admit us [to Paradise] with the righteous people."

So these christians are those that Allah will grant them Jannah for supporting and upon hearing the Quran recited shed tears.

But today, the Christians and Jews who died upon that faith will go to hellfire 

Reported from hadith,

It was narrated that ‘Abdullah said:

We were with the Messenger of Allah (ﷺ) in a tent, and he said: ‘Will it not please you to be one quarter of the people of Paradise?’ We said: ‘Yes.’ He said: ‘Will it not please you to be one third of the people of Paradise?’ We said: ‘Yes.’ He said: ‘By the One in Whose Hand is my soul, I hope that you will be half of the people of Paradise. For no one will enter Paradise but a Muslim soul, and among the people of polytheism you are like awhite hair on the hide of a black bull, or like a black hair on the hide of a red bull.’”

Sunan ibn Majah

Vol. 5, Book 37, Hadith 4283

May Allah continue to keep us upon the right path and die upon Islam. Aameen.