God created all things, so He makes the rules.  God gave Adam the responsibility for the whole garden.  Adam could eat whatever he liked, except for one thing. 

And the LORD God commanded the man, saying, Of every tree of the garden thou mayest freely eat: 17 But of the tree of the knowledge of good and evil, thou shalt not eat of it: for in the day that thou eatest thereof thou shalt surely die. (Gen. 2:16-17)

Sometimes, God’s restrictions don’t make sense to us.  As a matter of fact, we’re not sure why God gave this restriction.  However, God does not have to explain Himself.  After all, He’s God!

Instead of focusing on the restriction, we should focus on the permission.  Adam could eat from “every tree of the garden” except one.  It is easy to overlook God’s grace and goodness when we focus upon what we are not allowed to do.  God has given us so much freedom.  We should enjoy ourselves with those things which God wants us to have.

There are different views of the significance of the “tree of the knowledge of good and evil”.  Some see it as symbolic, but there is no reason to doubt that it was an actual tree.  Perhaps, the best way to understand it is as a tree which was not wholly different than any other tree, except that it was the one which God used to test Adam and Eve.  In other words, the fruit from it had no special power, but their disobedience is what caused it to be significant. 

Psalm 84:11 reads, “For the LORD God is a sun and shield: the LORD will give grace and glory: no good thing will he withhold from them that walk uprightly.”  Did you catch that?  God doesn’t withhold anything from us that is good.  The corollary of that is that He will withhold what is bad for us.  We just need to trust Him.  And Psalm 84:12 states just that, “O LORD of hosts, blessed is the man that trusteth in thee.”