Genesis 4:14

Behold, thou hast driven me out this day from the face of the earth; and from thy face shall I be hid; and I shall be a fugitive and a vagabond in the earth; and it shall come to pass, that every one that findeth me shall slay me.

1. Cain would no longer enjoy the privilege of speaking with God.
2. Cain worried that others would kill him.
3. There were other people on the earth besides Adam, Eve and Cain, so Adam and Eve must have had other children prior to Cain and Abel.
4. I'm uncertain what Cain meant by God driving him out from "the face of the earth." Obviously, he intended to continue living upon the earth.
5. We should not commit murder.