Hello Samuel
Nice to see you here again!
We believe Christianity, and all other religions and prophets sent by God ask their nations to submit to God, and God only.
In Quran, Surat Algen, Allah says to Mohammed:
(21) Say, "Indeed, I do not possess for you [the power of] harm or right direction."
(22) Say, "Indeed, there will never protect me from Allah anyone [if I should disobey], nor will I find in other than Him a refuge.
(23) But [I have for you] only notification from Allah, and His messages." And whoever disobeys Allah and His Messenger - then indeed, for him is the fire of Hell; they will abide therein forever.
All prophets ask their people to worship God, no one else. As Surat Ala'araf mentions that:
(59) We had certainly sent Noah to his people, and he said, "O my people, worship Allah; you have no deity other than Him. Indeed, I fear for you the punishment of a tremendous Day.
(65) And to the 'Aad [We sent] their brother Hud. He said, "O my people, worship Allah; you have no deity other than Him. Then will you not fear Him?"
(73) And to the Thamud [We sent] their brother Salih. He said, "O my people, worship Allah; you have no deity other than Him.
(85) And to [the people of] Madyan [We sent] their brother Shu'ayb. He said, "O my people, worship Allah; you have no deity other than Him. There has come to you clear evidence from your Lord. So fulfill the measure and weight and do not deprive people of their due and cause not corruption upon the earth after its reformation. That is better for you, if you should be believers.
The Surat Alanam confirms this from verse 70 to 88:
(70) And leave those who take their religion as amusement and diversion and whom the worldly life has deluded. But remind with the Qur'an, lest a soul be given up to destruction for what it earned; it will have other than Allah no protector and no intercessor. And if it should offer every compensation, it would not be taken from it. Those are the ones who are given to destruction for what they have earned. For them will be a drink of scalding water and a painful punishment because they used to disbelieve.
(71) Say, "Shall we invoke instead of Allah that which neither benefits us nor harms us and be turned back on our heels after Allah has guided us? [We would then be] like one whom the devils enticed [to wander] upon the earth confused, [while] he has companions inviting him to guidance, [calling], 'Come to us.' " Say, "Indeed, the guidance of Allah is the [only] guidance; and we have been commanded to submit to the Lord of the worlds.
(72) And to establish prayer and fear Him." And it is He to whom you will be gathered.
(73) And it is He who created the heavens and earth in truth. And the day He says, "Be," and it is, His word is the truth. And His is the dominion [on] the Day the Horn is blown. [He is] Knower of the unseen and the witnessed; and He is the Wise, the Acquainted.
(74) And [mention, O Muhammad], when Abraham said to his father Azar, "Do you take idols as deities? Indeed, I see you and your people to be in manifest error."
(75) And thus did We show Abraham the realm of the heavens and the earth that he would be among the certain [in faith]
(76) So when the night covered him [with darkness], he saw a star. He said, "This is my lord." But when it set, he said, "I like not those that disappear."
(77) And when he saw the moon rising, he said, "This is my lord." But when it set, he said, "Unless my Lord guides me, I will surely be among the people gone astray."
(78) And when he saw the sun rising, he said, "This is my lord; this is greater." But when it set, he said, "O my people, indeed I am free from what you associate with Allah.
(79) Indeed, I have turned my face toward He who created the heavens and the earth, inclining toward truth, and I am not of those who associate others with Allah."
(80) And his people argued with him. He said, "Do you argue with me concerning Allah while He has guided me? And I fear not what you associate with Him [and will not be harmed] unless my Lord should will something. My Lord encompasses all things in knowledge; then will you not remember?
(81) And how should I fear what you associate while you do not fear that you have associated with Allah that for which He has not sent down to you any authority? So which of the two parties has more right to security, if you should know?
(82) They who believe and do not mix their belief with injustice - those will have security, and they are [rightly] guided.
(83) And that was Our [conclusive] argument which We gave Abraham against his people. We raise by degrees whom We will. Indeed, your Lord is Wise and Knowing.
(84) And We gave to Abraham, Isaac and Jacob - all [of them] We guided. And Noah, We guided before; and among his descendants, David and Solomon and Job and Joseph and Moses and Aaron. Thus do We reward the doers of good.
(85) And Zechariah and John and Jesus and Elias - and all were of the righteous.
(86) And Ishmael and Elisha and Jonah and Lot - and all [of them] We preferred over the worlds.
(87) And [some] among their fathers and their descendants and their brothers - and We chose them and We guided them to a straight path.
(88) That is the guidance of Allah by which He guides whomever He wills of His servants. But if they had associated others with Allah, then worthless for them would be whatever they were doing.
God tells his final Prophet Mohammed peace and blessing be upon him in Quran at
Surat Alanbya:
(25) And We sent not before you any messenger except that We revealed to him that, "There is no deity except Me, so worship Me."
In response to your comment, Christians, who followed the real teachings of Eisa
peace be upon him, will go to heaven. However, the real teachings of Eisa
peace be upon him is to follow the final prophet and servant of God who be sent after him.
Eisa
peace be upon him came with good news, the good news was the final message, and
The Prophet that all nations will follow him, is about to be sent.
Allah confirms this in Quran that the only religion to follow is Islam.
(85) And whoever desires other than Islam as religion - never will it be accepted from him, and he, in the Hereafter, will be among the losers.