Sin is the violation of or the direct disobedience to the revealed will of God. It is also a state: the absence of righteousness, morality, honesty, or anything that falls short of the perfect glory of God. He has declared and established that the penalty for sin is eternal death.
This is what the Bible says about Sin -
“For whosoever shall keep the whole law, and yet offend in one point, he is guilty of all.” James 2: 10
“Therefore to him that knoweth to do good, and doeth it not, to him it is sin.” James 4: 17
“For all have sinned, and come short of the glory of God ... ” Romans 3: 23
“Behold, all souls are mine; as the soul of the father, so also the soul of the son is mine: the soul that sinneth, it shall die.” Ezekiel 18: 4
"All we like sheep have gone astray; we have turned every one to his own way; and the LORD hath laid on him the iniquity of us all." Isaiah 53: 6