Does God have the capacity to sin? Can God sin? To clarify,


this question is not asking for a "justification" of those times, described in the Bible, when God struck someone dead. Life is His to take. 
the question is also not asking strictly whether Jesus had the capacity to sin. The answer should not hinge on whether Jesus was God (He was, assume this), or whether Jesus was one or two persons (He was one divine Person, assume this). 


The question is asking if God can sin, with attention to, for example, how that might be reconciled with his omnipotence and benevolence. I expect that there are some theological constructs already in place to deal with this question or others like it. If there is some well-established theological difference between "can sin" and "has the power to sin" or "has the capacity to sin", then this should be clarified.

Can God (three Persons, one Being) sin?
God cannot sin, not because He lacks the free will to do so, but because it would be inconsistent with His character and His nature.

From http://www.godandscience.org/apologetics/rock.html


  The word "omnipotent" is never used in the Bible, but has been
  inferred primarily by one of God's Hebrew titles, "Shadday," which is
  most often translated "almighty."1 However, the Bible never claims
  that God can do all things. In fact, the Bible makes a point that
  there are things that God cannot do. The Bible says that God cannot
  commit sin.2 God cannot lie.3 Therefore, biblical omnipotence does
  not mean that God can do all things. God cannot do anything that is
  contrary to His holy character. However, God can do anything that He
  determines to do. This is a true meaning of omnipotence - the
  ability to do anything that one sets out to do.


Technically, God could sin if His nature were not perfect - if He chose to, but because His nature is Holy, Perfect, Flawless, to sin would be contrary to His nature.  He would never "set out" to do it,even if it is conceivably within HIs power to do so.

A pastor (I can't remember which) once put it like this:  "If I were to say I can't eat rotten garbage, that doesn't mean that it would be physically impossible for me to do so.  I have the physical capability to pick it up, put it in my mouth, chew, and swallow.  However, I say I cannot do it because it is so repulsive to me.  In this same way, it is possible for God to be omnipotent, yet be unable to sin."