If it wasn't, God wouldn't have allowed to be here. If we didn't have his word and couldn't trust in it, then we would have no instruction manual to live by and we would not be able to know the nature of God or his will for us. It can't be "some of it is the truth" and "some of it isn't." It is either the true word of God or none of it is!
"All Scripture is God-breathed and is useful for teaching, rebuking, correcting and training in righteousness, so that the servant of God[SUP]
a[/SUP] may be thoroughly equipped for every good work." (2 Tim.3:16)
"Above all, you must understand that no prophecy of Scripture came about by the prophet’s own interpretation of things. For prophecy never had its origin in the human will, but prophets, though human, spoke from God as they were carried along by the Holy Spirit. (2 Pet.1:20)
"I want you to know, brothers and sisters, that the gospel I preached is not of human origin. I did not receive it from any man, nor was I taught it; rather, I received it by revelation from Jesus Christ. (Gal.1:11)
"So when you see standing in the holy place ‘the abomination that causes desolation,' spoken of through the prophet Daniel—
let the reader understand—then let those who are in Judea flee to the mountains.
"Now the Berean Jews were of more noble character than those in Thessalonica, for they received the message with great eagerness and examined the Scriptures every day to see if what Paul said was true."
I'm like a Berean, I study the scriptures, therefore, if the pope or anyone else proclaims another gospel other than the one that I am reading about, then they are teaching a different gospel and are therefore, accursed. Scripture gets the final say.