Both Islam and Mormonism claim that God restored truth through later angelic revelation. Islam teaches that the Qur’an was delivered to Muhammad through the angel Jibril/Gabriel. Mormonism teaches that Joseph Smith was visited by heavenly messengers, especially Moroni, who directed him to the golden plates and the Book of Mormon.
But the Bible already gives a warning for exactly this kind of claim:
“But even if we, or an angel from heaven, should preach to you a gospel contrary to the one we preached to you, let him be accursed.”
Galatians 1:8
That verse is devastating because Paul does not say, “Believe it if it comes through an angel.” He says the opposite: even an angelic messenger must be judged by the apostolic Gospel already delivered.
The issue is not whether angels exist. Christianity absolutely affirms angels. The issue is whether a later “angelic revelation” contradicts the faith once delivered to the Church.
Jude writes:
“Contend for the faith that was once for all delivered to the saints.”
Jude 1:3
That phrase matters. Christianity is not waiting centuries later for a replacement Gospel, a corrected Jesus, a new scripture, or a restored priesthood invented after the apostolic age. The Church received the apostolic faith from Christ through the apostles, and that faith was to be guarded, not reinvented.
This creates a serious problem for both Islam and Mormonism.
Islam comes more than 600 years after Christ and denies central truths at the heart of the apostolic Gospel. The New Testament proclaims that Jesus is the Son of God, that He truly died by crucifixion, that He rose bodily from the dead, and that salvation is found in Him. Paul summarizes the Gospel clearly:
“Christ died for our sins in accordance with the Scriptures, that he was buried, that he was raised on the third day…”
1 Corinthians 15:3–4
But the Qur’an denies that Jesus was crucified in the Christian sense, saying, “they did not kill him, nor did they crucify him” (Qur’an 4:157). It also rejects Jesus as the divine Son of God. That is not a minor disagreement. It strikes at the center of the Christian Gospel.
Mormonism also claims later angelic and prophetic restoration, but it introduces teachings foreign to biblical and historic Christianity: additional scripture, restored priesthood authority, temple ordinances, exaltation, eternal progression, and a radically different view of God and man than the faith confessed by the ancient Church. The New Testament teaches one God, one Lord Jesus Christ, and one apostolic Gospel. Mormonism claims that the Church fell into apostasy and needed restoration through Joseph Smith.
But if the entire Church lost the true Gospel, then Christ’s promise failed:
“I will build my church, and the gates of hell shall not prevail against it.”
Matthew 16:18
From an Orthodox Christian perspective, this is one of the deepest problems with both Islam and Mormonism. Both depend on the idea that the historic Christian Church became so corrupt that God had to send a later corrective revelation. But the biblical pattern is not “wait for a new prophet centuries later to replace the apostolic faith.” The biblical pattern is: guard what was handed down.
Paul tells Timothy:
“Guard the deposit entrusted to you.”
1 Timothy 6:20
And again:
“Follow the pattern of the sound words that you have heard from me… guard the good deposit entrusted to you.”
2 Timothy 1:13–14
The apostles did not tell Christians to expect a future religion that would overturn their message. They warned that false teachers would arise, even with spiritual claims. Paul says Satan can disguise himself as “an angel of light” (2 Corinthians 11:14). John commands believers to “test the spirits” rather than blindly accept every spiritual claim (1 John 4:1).
So the biblical test is clear:
Does the later revelation confess the same Christ, the same Gospel, and the same apostolic faith?
Islam says Jesus was not the crucified and risen Son of God in the Christian sense.
Mormonism says the apostolic Church fell away and needed restoration through Joseph Smith, along with new scripture and doctrines unknown to the ancient catholic and apostolic Church.
Both claims collide with the biblical command to preserve the faith already delivered.
That is why Galatians 1:8 is so powerful. Paul does not merely warn against human false teachers. He specifically includes the possibility of an angelic messenger. The authority of the Gospel does not come from how supernatural the messenger appears. It comes from whether the message agrees with the apostolic Gospel of Jesus Christ.
So if an angel appears centuries later and announces a different Jesus, a different Gospel, or a different faith than the one delivered by Christ and His apostles, the Bible already tells Christians what to do:
Reject it.
Not because Christians are afraid of revelation, but because God has already spoken decisively in His Son, through His apostles, and in the faith once for all delivered to the saints.
Sources
The Holy Bible: Galatians 1:6–9; Jude 1:3; 1 Corinthians 15:1–4; Matthew 16:18; 1 Timothy 6:20; 2 Timothy 1:13–14; 2 Corinthians 11:14; 1 John 4:1
Qur’an 4:157
https://quran.com/4/157
Qur’an 112:1–4
https://quran.com/112
Joseph Smith—History 1, account of Moroni’s visit
https://www.churchofjesuschrist.org/study/scriptures/pgp/js-h/1
LDS Gospel Topics: Book of Mormon Translation
https://www.churchofjesuschrist.org/study/manual/gospel-topics/book-of-mormon-translation
LDS Gospel Topics: Priesthood Restoration
https://www.churchofjesuschrist.org/study/manual/gospel-topics/priesthood-restoration