It Isn't In The Book
The common conception in the denominational world with reference to faith is that it does not matter what a man believes just so he is honest. To put it another way, "One faith is just as good as another". This goes along with the idea, "One church is just as good as another" therefore "Join the church of your choice". Such people have no convictions and are "anythingarians" in religion. In some respects that is worse than a "Nothingarian". At least it is more apt to keep one complacent and deceived.
It would be interesting to study the use of the term "The Faith" as it is employed in the New Testament. Look at these and other passages that are similar:
Acts 24:24. The Faith in Christ Jesus.
Gal. 1:23, Preacheth The Faith.
Acts 6:7. Obedient to The Faith.
Acts 13:4. Turn aside from The Faith.
Acts 14:22. Exhort to continue in The Faith.
Acts 16:5. Strengthened in The Faith.
Eph. 4:4. One Faith.
Phil. 1:27. Striving for The Faith.
Jude 3. "Contend earnestly for The Faith once delivered".
II Tim. 4:7, "Kept the Faith".
Of course anyone should know who has read the Bible any at all that "Many Faiths" are not taught in the scriptures. God has revealed and Christ has authorized but "one Faith". It is just as much a contradiction of God's Word to teach "many faiths" as it would be to teach "many Christs" or "many Gods".
Jesus said that every one who does not believe the Gospel will be damned. Mark 16:15-16. Paul said that those who believe not the truth would be damned for that very reason. 2 Thess. 2:11-12. Our faith should be in the Lord and His word. Not in our own opinions and the wisdom of man.
The notion that it doesn't matter what a man believes just so he is honest is pure nonsense anywhere it is applied. Consider the application of such an idea in the financial world. A man gathers together his life's savings and invests them in a business that is on the verge of bankruptcy believing with all confidence that it is in a going and profitable condition. When the investment has been made he discovers that it is only an interest in a debt which he has bought. Would his "believing in it sincerely" keep him from losing his money? No one would so contend.
Suppose again that an evil reprobate wins the confidence of a fine young lady. Would the fact that she trusts him prevent her from suffering the misery he would be sure to bring into her life? Who would say so? Suppose a man exerts himself above the strength of his heart thinking that he is perfectly sound and strong physically, would it save him from a heart attack because he thought himself to be all right? Surely not. The idea that it doesn't matter what one believes just so he is honest is just as ridiculous in religion as it is elsewhere. Thinking people will not accept it anywhere. It simply says that it does not matter whether or not a man believes the truth, error will do just as well. It contends that it doesn't matter whether or not a man believes what God has said, if he is only honest. That, of course, means that it doesn't matter what God has said. This is exactly the opposite of what the Bible teaches.
The only reason for being anything in religion is because you believe in it. The only reason for believing anything in religion is because God said it. "Faith comes by hearing the Word of God." Rom. 10:17. Why do you believe it? Where did God ever say it?
The idea that it doesn't matter what you believe just so you are honest just "Isn't in the Book"! The Book teaches exactly the opposite to that.