The divine law of love towards God and neighbor commands us that we not only do good to our neighbor but also avoid doing evil. One of the greatest evils to the other person is to kill and thus deprive the person’s right to live.
Hence the Fifth Commandment says: “Thou shalt not Kill”
In this Commandment, God forbids us to destroy our own life and that of our neighbor as well. Positively this Commandment teaches us that it is our duty to protect our own life and that of our neighbor. Based on this, both suicide and murder are sins against fifth Commandment.
Why suicide is sin? It is because the body belongs to God (Cfr.1 Corinthians 6:13), not because He created it but because Christ has bought it with a price (Cfr.1 Corinthians 6:20). We are like a tenant not the owner, who has no right to damage or destroy or cause grave injury to our body. Hence St. Paul instructs us “Let not sin therefore reign in your mortal bodies, to make you obey their passions. Do not yield your members to sin as instruments of wickedness, but yield yourselves to God as men who have been brought from death to life, and your members to God as instruments of righteousness” (Romans 6:12-13).
However, it is meritorious to sacrifice one’s body or bodily health, in order to gain everlasting life or to rescue someone from physical or spiritual death. Thus, martyrdom is meritorious; so also, is meritorious, the death of doctors, nurses, priests and all others, who attend those who have an infectious disease. Risking one’s life to rescue another person, who has fallen into the fire or water or to expose oneself in battle for the defense of the country is meritorious.
We have the duty to regard the life of our neighbor. Accordingly, it is sinful to cause grave injury and put someone to death unjustly and intentionally. Nevertheless, during self-defense, if the attacker gets killed, it is justifiable and lawful, because one has a right of self-defense.
Basically, the Fifth Commandment expects from us that we understand the value of our own body and the gift of life and that we take care to keep it healthy till the end of our journey on the earth.
God bless you
Fr. Arul Joseph V.