"Therumeni, there is one question in my mind since long, which is; "is it a necessity to confess one's sins before a Priest or a Bishop. if so, where can we find such a direction in the Holy Bible". If I directly go and ask forgiveness from the person, whom I may have sinned; will my sins be not forgiven?"
Thank you for your question.
First of all let me tell you that proof texts for many of the practices of our Church, for that matter any Church, may not be found in the Bible. This raises the question of our understanding of the Bible. Bible is not a text book for our religious practices that were introduced by the fathers of the Church on the basis of need of time and situation. Bible is, rather, a book of principles. Principles are, in most cases, universal and practices are local and time-situation bound. We make practices on the basis of principles laid out in the Bible. Personal confession is one among them. Setting relationships right is a principle laid out by Jesus himself as per the testimony of the Biblical writers (Matthew 5:23, 24).
Again confession is not just for the forgiveness of sins. It is an expression of the self before someone who is competent, authorised and qualified to listen and respond. This has several dimensions. Confessing sin is just one among them.
In our life in this world we will have to go through lot of situations. These situations may bring joy, sorrow, grief, sadness, sorry, anger etc. etc. You need to find people to share these moods and feelings with someone. Any mood or feeling you may have will have religious, psychological, emotional, relationship, social and community elements in it. For example when you are happy, it may be because you had something happened to you or someone did something for you. You may not know some times who did what. But in any situation there will be two elements that influence it. First, God who monitors and be present to help us to take that situation to a positive ending. Second, the creation of God that influences the other in some way or other. So you need someone who can represent both God and creation to share the joy. The Church has provided us with a person who represents both, and that is a priest.
Again when you are sad or sick, that may have caused by something (event) or by someone. Even if you know who or what caused it, you may or may not be able to take it up directly with that person or thing. Even though you may know it will be God alone who can deal with your sadness in an effective way. So you need someone who can represent God. Further you also need to have a person to who can represent the community. That is what a priest is. Since the priest is the representative of the people, he can represent the prayers of the people before God. The very knowledge that there are lot of people who are concerned of your welfare and who are praying for you will help you deal with your situation. These prayers will be of greater value before God also (see James 5:14). Sometimes you may feel sorry for what you did or said or thought. You may not know how many people were affected by that. It will be good to say sorry to the person whom you know was affected by that. But that person alone may not have been affected. Anything we do will have consequence far reaching than we may think. We may assume that only just one person or few people were affected by what we did, said or thought. But many a time it may affect lot of people and nature beyond our imagination. So just saying sorry to the person whom you think was affected will not be enough to take away the guilt. If we do sin against nature, we can not go and tell sorry to nature. Then we need a person who can represent both God and His creation. Also, if you go and express sorry directly to a person whom you think may have been affected, it may cause further problems as that person may not see things as you see it and respond the way you wanted that person to be. When we are sorry about something wrong we did, said or thought we need to be absolved of that. When we reveal the matter to a priest, he is authorized and designated by the community and God through the ordination he received to absolve and pardon the wrong doing on behalf of God and on behalf of creation. The priest will be able to suggest a remedy too. He may be able tell you whether you can or need to go to the person concerned and say sorry. This has a psychological effect too.
Again people may ask why we cannot just say that to God. That is a possibility. But that is something which has no personal presence. When you say something, you need to have someone to listen to in person, need someone to talk back to you in terms of that it was well understood and also to suggest some solution. The Church provides such a person in a priest. Further confession provides a possibility of counselling free of cost. Sometimes you may feel that you have to talk to someone who can personally listen and suggest a solution. That person should be someone in whom you can trust also. A priest is bound by law in the Church that whatever others share with him in confession should not be shared to anyone. So personal confession is a great and valuable possibility the Church has set for people to be healthy in mind and spirit.
Regards and prayers