Psalms 66:18 says: “If I had ignored my sins, the Lord would not have listened to me.” This verse clearly says that if we want our prayers to be heard by the Almighty God, then we cannot ignore our sins; we have to repent of our sins and confess them to obtain forgiveness.
But, what actually is sin?
SIN: Self Inflicted Nonsense / Self Induced Negativity.
This was how Susannah Wesley defined "sin" to her young son, John Wesley: "If you would judge of the lawfulness or the unlawfulness of pleasure, then take this simple rule: Whatever weakens your reason, impairs the tenderness of your conscience, obscures your sense of God and takes off the relish of spiritual things - that to you is sin."
Pro 28:13 says: “You will never succeed in life if you try to hide your sins. Confess them and give them up; then God will show mercy to you.”