I agree with the replies.

It is too simple to make a sweeping generalization "open source is more secure" or "open source is less secure".

So, anyone who believes either statement, yes or no, is both right and wrong, because the statement is too general and therefore meaningless

Even the term "security" has no real meaning. In discussing IT security you must discuss risk, and to discuss risk you must think in terms of vulnerability, threat and impact.

For example, an open source system turned on and sitting in your closet without a connection to the Internet may be more secure that the most expensive closed source system on the Internet

In other words, there are security experts born every minute, it seems, and very few understand what they are actually taking about. If you understood security and risk management, you could not answer such a simple question as "is open source more or less secure?" because this question has no context and just lends to endless, meaningless debates by people who do not understand the nature of IT security and risk management.