Summary: Those who say: "it doesn’t matter what you believe so long as you are sincere" are espousing a very dangerous and false doctrine. It really does matter what you believe.
IT DOES MAKE A DIFFERENCE WHAT YOU BELIEVE
“Now the just shall live by faith; but if anyone draws back, My soul has no pleasure in him. But we are not of those who draw back to perdition, but of those who believe to the saving of the soul.” Hebrews 10:38-39
The statement "It doesn’t matter what you believe so long as you are sincere" is infinitely more dangerous in one’s spiritual life than in the physical world in which we live. Having a wrong belief in the physical world may lead to injury, sickness or death but in the spiritual world it ends in eternal death.
Years ago, in a high school chemistry class, a little humorous poems was making the rounds. It went like this:
Alas for little Willie,
We’ll ne’er see Willie more,
For what he thought was H2O
Now we can scarcely imagine anyone making such a ridiculous misjudgment as mistaking sulphuric acid for water, but far worse a fate awaits those who accept a nebulous, convictionless religion instead of experiencing a life-changing faith in our Lord Jesus Christ.
The scripture concludes: "There is a way which seems right to a man, but its end is the way of death." Proverbs 14:12.
I. WHAT WE BELIEVE MAKES A DIFFERENCE IN EVERY AREA OF LIFE.
In our physical life, it matters in regard to food, drink, medication, or environmental exposure. Our ignorance of the consequence does not minimize the danger. How often have we said: "I thought it was good"; "I thought it was safe"; "I really didn’t think it mattered"; "I really thought that it was a good investment", etc. only to find out that it really did matter.
II. LIFE’S MOST TRAGIC MISCALCULATION...BEING WRONG SPIRITUALLY!
Its temporal consequences:
The religious zealot who believes that only his little group shall be saved to the exclusion of every other believer:
The irresponsible sectarian who permits his child to die (or suffer) rather than take him to a doctor…or permit him to have a blood transfusion:
The haughty and proud who manifest a "holier than thou" attitude.
Its eternal consequences: eternal damnation upon oneself and upon others who look to them for instruction, advice, leadership or example.
III. HOW CAN WE BE SURE WE HAVE THE RIGHT BELIEF?
God’s Word, the Holy Bible, is our only sure and certain guide.
Be sure you have the right belief concerning God! (Hebrews 11:6)
Be sure you have the right belief concerning yourself! (Romans 3:23)
Be sure you have the right belief concerning God’s plan for your salvation! (John 3:16).