(The following is from the 1689 Baptist Confession of Faith in Modern English. Editor's note: This gem is filled with sound doctrine—so it needs to be read carefully.)
From all eternity God decreed all that would happen in time—and this He did freely and unalterably, consulting only His own wise and holy will. Yet in so doing He does not become in any sense the author of sin, nor does He share responsibility for sin with sinners. In this decree God's wisdom is displayed in directing all things—and His power and faithfulness are demonstrated in accomplishing His decree.
God's decree is not based upon His foreknowledge of the future—but is independent of all such foreknowledge.
By His decree, and for the manifestation of His glory—God has predestined (or foreordained) certain men and angels to eternal life through Jesus Christ, thus revealing His grace. Others, whom He has left to perish in their sins, manifest the terrors of His justice.
These predestined and foreordained angels and men are individually and unchangeably designated—and their number is so certain and definite, that it can neither be increased or decreased.
Before the world was made, God's eternal, immutable purpose, which originated in the secret counsel and good pleasure of His will, moved Him to choose (or to elect), in Christ—certain men to everlasting glory. Out of His mere free grace and love, He predestinated these chosen ones to life, although there was nothing in them to cause Him to choose them.
Not only has God appointed the elect to glory in accordance with the eternal and free purpose of His will—but He has also foreordained the means by which His purpose will be effected.
Therefore, those who are elected, being fallen in Adam—are redeemed by Christ and effectually called to faith in Christ by His Spirit working at the appropriate time. They are justified, adopted, sanctified, and kept by His power through faith to salvation. None but the elect are redeemed by Christ, or effectually called, justified, adopted, sanctified, and saved.
The doctrine of the high mystery of predestination is to be handled with special prudence and care so that those heeding the will of God revealed in His Word and obeying Him may be assured of their eternal election, by the certainty of their effectual calling. In this way the doctrine of predestination will give reasons for praise, reverence, and admiration of God—as well as humility, diligence and rich comfort to all who sincerely obey the gospel.