Not only by the name of “good Friday†have we called this day. In different countries it is known by different names. In Latin America, France Italy, Vietnam, Japan, Brazil, Portugal, Spain, Philippines is called as “holy Fridayâ€, “Mourning Friday†in Germany, “long Friday†in Denmark, Finland, Iceland, Sweden and “sad Friday†in some Arabic and Asian countries. So now here the question is that why is it known as “good Friday†in English speaking land? It is observed as the day marking death of Jesus Christ on cross on 3rd April A.D 33. According to western church’s liturgical calendar it was the last Friday before Easter and an adjective of “good†is attached to it which was taken as the similar meaning of “holy†in old English.
If it was named as “sad†or “mourning†Friday the people might have observed it as a sad day so that might be one reason why it is given the adjective “goodâ€. Another reason for it may be that it was a great victory of Jesus Christ over the evils like death, devil and sin. It is said that he took on himself all the sins of mankind for once so it was a gift for all mankind. Some think that the word “good†and “god†has been mixed up as they are spelled almost similarly. So it may be “god’s Friday†which has now changed to “good Friday†like the phrase “god be with you†has now changed to “good byeâ€. So we can say that it might have happened with the “good Friday†and is celebrated all over the world.