“But even if we, or an angel from heaven,
preach any other gospel to you
than what we have preached to you,
let him be accursed.
As we have said before, so now I say again,
if anyone preaches any other gospel to you
than what you have received,
let him be ACCURSED.”
Galatians 1:8-9

Tough words. And he emphasizes it by stating it twice.

Why?

Because man is lost and God has only given one atonement for us, his Son Jesus Christ. That atonement is the ONLY way that we can be saved.

Satan hates the Gospel, and he constantly tries to turn the eyes of mankind away from it. He has many counterfeits and he works intensely at bringing people into the deception perpetrated by those counterfeits. There are such dire consequences to that, that the Scriptures pronounce a curse upon anyone who brings a “gospel” other than the true one, or who suggests a way other than the way of Jesus Christ. And it mentions specifically those brought by a supposed angel, for example, the “angel” Moroni of the Mormons, or the “angel” who supposedly gave Mohammed his deceptive message resulting in Islam. These are actually under the CURSE of almighty God.

There is only one way.    All else it counterfeit.

“I AM the way, the truth, and the life.
No one comes to the Father except through me.”
John 14:6

“For there is one God
and ONE mediator between God and men,
the man Christ Jesus.”
1st Timothy 2:5

“Nor is there salvation in any other,
for there is NO OTHER name under heaven
given among men by which we must be saved.”
Acts 4:12

See:
Who Is God?