In the opening pages of Ender’s Game, Ender observes that “Sometimes lies were more dependable than the truth? What does he mean by that? In the opening pages of Ender’s Game, Ender observes that “Sometimes lies were more dependable than the truth. Do you think his
observation is correct or incorrect?

He means that there are situations where lying brings us comfort, because reality is very difficult to face.

Explanation:

Ender, I meant that sometimes the lies show us a false reality, but comfortable and that it gives us a good and credible feeling. This is because the reality of this situation is cruel and difficult to accept, difficult to promote credibility, because it does not bring comfort to human beings, even if it is real. Ender is right in his observation, however, it is always beneficial for us to face the truth about things, even if it is uncomfortable, than to live in a lying illusion that will soon end.

taking into account that a theme is the central topic a text treats and can be developed through a story, play, poem etc. the following are themes that can be further developed:  

my best friend jeffrey has many unusual interests. (the story could be about each of the unususal interests)

once a man gives his soul over to evil, he can never go back. (this could be a saying or a proverb)

the three sheepdogs lay around the yard all day. (it could be developed detailing how each of these sheepdogs lay around)

a priest's collar has an unusual effect upon people. (it could be developed detailing the different effect upon people)

innocence is a powerful force in a world full of corruption. (it could be developed detailing how is a world full of corruption)

king lear is a play shakespeare wrote later. (it is just a sentence and doesnt give any idea or topic to be discussed in details.

evil often wears the disguise of innocence. (this could be a saying or a proverb)

you need to make an explanation. so, since you did not include one, so no one, and i mean no one can unfortunately you,