Epeide is a causal conjunction appearing 10 times in the New Testament, combining epei (since/because) + de (now/but) for emphasis. It introduces the reason or basis for a preceding statement — often in Paul's epistles where it grounds theological argument in observable fact or divine action. It is the word of 'given that...' reasoning — acknowledging a reality that then determines a course of action.
Epeide anchors some of Paul's most powerful arguments. In 1 Corinthians 1:21, 'Since [epeide] in the wisdom of God the world through its wisdom did not know him, God was pleased through the foolishness of what was preached to save those who believe' — the cross as God's counterintuitive response to human intellectual failure. Luke 1:1 uses it to ground his Gospel account: 'Since [epeide] many have undertaken to draw up an account...' — historical reality demands historical record. Epeide trains biblical reasoning to start with facts and follow where they lead.