I’m in Job chapter 7 and the king of complaining continues…

I can say what I want. [Job 7:11]

Life sucks. [Job 7:16]

What did I do to you? [Job 7:20]

Give me a break! [Job 7:21]

My Bible’s commentary says:

“Although Job had lived a blameless life, he was beginning to doubt the value of living in such a way.  By doing this, he was coming dangerously close to suggesting that God didn’t care about him and was not being fair.”

Is it a sin to say “it’s not fair”?

I understand that we are not to curse God or blaspheme God,

“You shall not take the name of the LORD your God in vain, for the LORD will not hold him guiltless who takes his name in vain.”   Exodus 20:7

blas·phe·my    noun    \ˈblas-fə-mē\

Definition:
1 a : the act of insulting or showing contempt or lack of reverence for God
   b : the act of claiming the attributes of deity
2 : irreverence toward something considered sacred or inviolable

but is questioning Him or saying “it’s not fair” cursing Him?

That depends on our heart.

Yes, God wants us to share our heart with Him; our concerns, dreams, struggles, desires, needs and worries…

“casting all your anxieties on him, because he cares for you.”   1 Peter 5:7

but we must have the right attitude,

“Humble yourselves, therefore, under the mighty hand of God so that at the proper time he may exalt you,”   1 Peter 5:6

and be willing ultimately to follow His plan no matter the consequence.

“…Nevertheless, not my will, but yours, be done.”   Luke 22:42b

God is not a magic genie that we can call on whenever we want something.  He doesn’t just show up to fulfill our every whim.

Job lived a righteous life and it seems he deserved the right to blame or turn His back on God.  But Job knew God; he learned God’s truths and promises, appreciated what God had given and trusted Him when He took it away.

But Job was not perfect; he questioned, he didn’t understand and he complained.

Makes him a bit more human, doesn’t it?

Be careful from where your complaints stem.  God wants us to share our hearts with him, but make sure it’s a heart of obedience not obstinance.