I love a good popular etymology as much as anyone, and the standard explanation for the word “sincere”  is no exception.  It is often said that the English word “sincere” is derived from the Latin sine “without” and cera  “wax.” According to this  popular explanation, potters in ancient Rome filled chips and cracks in their pottery with wax to hide them.  As a result, a “sincere” or “without wax” vessel would be a true and honest one.  

Popular etymologies such as this one are often so much more fun than the reality, but a quick check of The Oxford English Dictionary will show that scholars  believe “sincere” is actually derived from the Latin sincerus meaning clean, pure.  The word’s original meaning  is likely “one growth” (as in pure and unmixed seed or crops ), from sin  “one” and crescere  “to grow.”
Certainly, in ancient Latin the word sincere could refer to anything that had not been adulterated, such as  “sincere wine”  which, rather than not having wax added, simply had not been watered down.  Such wine – or any other unadulterated substance – was “true” and “without deceit,” as we use the word today.

It’s a meaning we can ponder.  When Jesus first saw Nathanael and exclaimed “Behold, an Israelite indeed, in whom there is no deceit!” (John 1:47), it is clear that he referred to the man’s sincerity.   This is the clear meaning of Ephesians 6:5 also:  “Slaves, obey your earthly masters with respect and fear, and with sincerity of heart, just as you would obey Christ.”  Here Paul’s words show that servants are to have “sincerity of heart” and not be duplicitous – truly serving their masters and God rather than just appearing to do so. 

In his second letter to the  Corinthians, however,  Paul pushes the idea of sincerity a step further in calling on the Corinthians to support the believers in need in Jerusalem: “I am not commanding you, but I want to test the sincerity of your love by comparing it with the earnestness of others” (2 Corinthians 8:8).

In saying this Paul suggests that our sincerity can be tested by the degree of our love for others.  It’s easy to think that as long as we tell the truth and mean what we say we are sincere,  but in this wider sense  “sincere” Christians are those who not only truthfully mean what they say and do, but also those who can be seen to be truly following through in their beliefs.  The distinction might seem small if we don’t think about it, but it’s really a large one – it’s the difference between wine that has been watered down and the 100% full strength item. 

From this perspective, according to Paul,  sincerity goes well beyond meaning what we say and do; it also involves our commitment to doing what we know we need to do.   If we can follow through in this fullness of sincerity, we may not “have it made” as George Burns intimated, tongue in cheek, but we will definitely be heading in the right direction.