Please correct it! thanks guys!

Is the death penalty effective?

In Italy, the death penalty has not really been established yet, thanks to the Catholic Church, which highly dominates the laws in this country. In fact, Vatican is still asking for driving out the death penalty completely.
However, people who are accused for committing crimes ends up appealing the court for years even though they have already been sentenced. That does not make much sense.
Firstly, I believe the death penalty is very effective for any convict because if somebody kills another person he has to pay. Cutting down sentences is like to leaving them homicidal free.
Secondly, the only way to avenge the death of our relatives is by death penalty.
Finally, I believe convicts have to suffer the consequences for their actions in the same way as a result of their action. 
I also think that if Italy officially applied the death penalty for homicides and rapes, there would be fewer innocent dead people.