We know Xianity is false because Jesus prophesied that he would return within the lifetime of his then present-day followers to bring Judgment Day, the end of the world, to which Xians eagerly look forward, to this day.
And he said unto them, Verily I say unto you, That there be some of them that stand here, which shall not taste of death, till they have seen the kingdom of God come with power.
From those, too, who call themselves Christians, We did take a covenant, but they forgot a good part of the message that was sent them: so we estranged them, with enmity and hatred between the one and the other, to the day of judgment. And soon will Allah show them what it is they have done.
But some of the desert Arabs believe in Allah and the Last Day, and look on their payments as pious gifts bringing them nearer to Allah and obtaining the prayers of the Messenger. Aye, indeed they bring them nearer (to Him): soon will Allah admit them to His Mercy: for Allah is Oft-forgiving, Most Merciful.
No One knows when the Day of Resurrection will come except Allah
Here Allah tells His Messenger that he cannot know when the Hour will come, and if people ask him about that, He instructs him to refer the matter to Allah, may He be exalted, as Allah says in Surat Al-A`raf, even though that was revealed in Makkah and this Surah was revealed in Al-Madinah. Allah continues to tell him to refer this matter to the One Who knows about it, but He tells him that it is at hand, as He says:
(What do you know It may be that the Hour is near!) This is like the Ayat:
(The Hour has drawn near, and the moon has been cleft asunder.) 54:1
This hadith has been reported by Sahl b. Sa’d that he heard Allah’s Messenger (ﷺ) as saying:
I and the Last Hour are (close to each other) like this (and he, in order to explain it) pointed (by joining his) forefinger, (one) next to the thumb and the middle finger (together).
Anas b. Malik reported that Allah’s Messenger (way peace be upon him) said:
I and the Last Hour have been sent like this. Shu'ba said: I heard Qatada as saying in his narration: The excellence of one over the other. And I do not know whether he narrated it from Anas or Qatada himself said so.
I heard Qatada and Abu Tayyab narrating that both of them heard Anas as narrating that Allah’s Messenger (ﷺ) said: I and the Last Hour have been sent like this, and Shu'ba drew his forefinger and middle finger near each other while narrating it.
‘A'isha reported that when the desert Arabs came to Allah’s Messenger (ﷺ) they asked about the Last Hour as to when that would come. And he looked towards the youngest amongst them and said:
If he lives he would not grow very old that he would find your Last Hour coming to you (he would see you dying).
Anas reported that a person asked Allah’s Messenger (ﷺ) as to when the Last Hour would come. He had in his presence a young boy of the Ansar who was called Muhammad. Allah’s Messenger (ﷺ) said:
If this young boy lives, he may not grow very old till (he would see) the Last Hour coming to you.
Anas b. Malik reported that a person asked Allah’s Apostle (ﷺ):
When would the Last Hour come? Thereupon Allah’s Messenger (way peace be upon him) kept quiet for a while. Then looked at a young boy in his presence belonging to the tribe of Azd Shanu'a and he said: If this boy lives he would not grow very old till the Last Hour would come to you. Anas said that this young boy was of our age during those days.
A young boy of Mughira b. Shu'ba happened to pass by (the Holy Prophet) and he was of my age. Thereupon Allah’s Apostle (ﷺ) said: If he lives long he would not grow very old till the Last Hour would come (to the old people of this generation).
That young boy is long dead.
Muhammad was also a false prophet, therefore Islam is alsofalse.