The God of glory appeared unto our father Abraham (Acts 7:2). How God appeared to Abraham, we are not told; but it was the first of seven communications to Abraham recorded in Genesis. The revelation of Gods glory would have shown Abraham the vanity and folly of the idol worship in Ur. Who wants to worship a dead idol when he has met the living God! First Thessalonians 1:910 and 2 Corinthians 4:6 describe this salvation experience.
But God also spoke to Abraham (Gen. 12:13), and the Word brought about the miracle of faith. So then faith cometh by hearing, and hearing by the word of God (Rom. 10:17, kjv). It was a call to separate himself from the corruption around him, and Abraham obeyed by faith (Heb. 11:8). True faith is based on the Word of God and leads to obedience. God could not bless and use Abraham and Sarah unless they were in the place of His appointment (2 Cor. 6:147:1).
Lost sinners today are not likely to receive a special revelation of Gods glory as did Abraham and Sarah. But they can see His glory in the lives of His people (Matt. 5:16) and hear His Word of faith when they share their witness. God spoke to Abraham directly, but today we hear the truth of salvation through the witness of His people (Acts 1:8).
Christs promise: "You will receive power when the Holy Spirit comes on you; and you will be My witnesses in Jerusalem, and in all Judea and Samaria, and to the ends of the earth" (Acts 1:8, niv).
Source: Through the Year