Did Evil enter the World when Man sinned, or was sin already in the World but man did not know what it was?
We know from Genesis chapter three that there was a time when Adam and Even were not sinful and a time after. We also know that the Bible says that through one man sin entered the world.
Romans 5:12 Wherefore, as by one man sin entered into the world, and
death by sin; and so death passed upon all men, for that all have
However, there was evil intent in Satan lying to Eve and this evil may not have been recognized by Adam and Eve as they had not eaten of the tree of the knowledge of good and evil at that point.
The evil in Satan can be seen as in evidence prior to the sin of Adam and Eve. However, the origin of this evil is not specifically laid out for us. We do have a hint that while written to the king of Tyrus, seems to apply to the power behind him;
Ezekiel 28:12-19 Son of man, take up a lamentation upon the king of
Tyrus, and say unto him, Thus saith the Lord GOD; Thou sealest up the
sum, full of wisdom, and perfect in beauty. (13) Thou hast been in
Eden the garden of God; every precious stone was thy covering, the
sardius, topaz, and the diamond, the beryl, the onyx, and the jasper,
the sapphire, the emerald, and the carbuncle, and gold: the
workmanship of thy tabrets and of thy pipes was prepared in thee in
the day that thou wast created. (14) Thou art the anointed cherub
that covereth; and I have set thee so: thou wast upon the holy
mountain of God; thou hast walked up and down in the midst of the
stones of fire. (15) Thou wast perfect in thy ways from the day that
thou wast created, till iniquity was found in thee. (16) By the
multitude of thy merchandise they have filled the midst of thee with
violence, and thou hast sinned: therefore I will cast thee as profane
out of the mountain of God: and I will destroy thee, O covering
cherub, from the midst of the stones of fire. (17) Thine heart was
lifted up because of thy beauty, thou hast corrupted thy wisdom by
reason of thy brightness: I will cast thee to the ground, I will lay
thee before kings, that they may behold thee. (18) Thou hast defiled
thy sanctuaries by the multitude of thine iniquities, by the iniquity
of thy traffick; therefore will I bring forth a fire from the midst of
thee, it shall devour thee, and I will bring thee to ashes upon the
earth in the sight of all them that behold thee. (19) All they that
know thee among the people shall be astonished at thee: thou shalt be
a terror, and never shalt thou be any more.