All false doctrine has its roots in truth, which is what makes it believable! Just like rat poison, false doctrine does not need much error to be deadly.
Consider this… How many grains of sand would I have to put into a jar of honey to make it not 100% pure honey?
How much leaven (yeast) does it take to raise a whole lump of dough? – (the metaphor Jesus used in His teaching for the false doctrine of the Pharisees – Matt. 16:6-12; Gal. 5:7-9).
Not to make too much use of examples, but this is a very clear illustration of the dangers of a small deviation from true and sound doctrine…
In a ship’s navigation, all it takes to leave New York heading for Portugal, Spain only to arrive at Western Sahara, Africa is a small percentage of a degree. The further you follow that line, the greater the distance from your intended destination!
Today there are those who believe that because Jesus did in fact, deal with sin once for all on the cross (Heb. 7:27; Heb. 9:12; Jude 1:3) there is, no need to come to Him for forgiveness of individual sins once you are born again. While the doctrine of sin being paid for ONCE FOR ALL is 100% correct, the conclusion that this means forgiveness for individual sins once one comes to Christ is unnecessary, is false.
Let me interject here that any interpretation of scripture, which is not straight forward and obvious, but has to be looked at a certain way in order for it to make any sense, is (in my opinion) immediately suspect.
To be certain, passages which are difficult to understand exist. The true litmus test of accurate interpretation of scripture is – does it agree with the whole of what scriptures teach on the given subject.
I say these words with no animosity intended. In fact, I speak from experience. I have done the same thing and so I recognize the symptoms.