Calvinism is the theological system which teaches that God is supremely Sovereign over all things in creation, including the salvation of mankind.
According to the Lexham Glossary of Theology, “Calvinism emphasizes human sinfulness, predestination, justification by grace through faith alone, the authority of the Scriptures, and a high view of God’s sovereignty.”
Calvinism is most easily understood by the acronym T.U.L.I.P which was constructed by the followers of John Calvin shortly after his death; in response to the teachings of Jacobus Arminius’s followers, best known as the 5 points of Arminianism.
The T.U.L.I.P defined
T– Total Depravity teaches that mankind is by nature opposed to God. According to scripture man is unable to save himself. He is dead in his sin. He is blind to the message of the Gospel, and he is in willful disobedience to the authority of God over his life. In his natural state mankind is in bondage to his evil nature and apart from a supernatural work of the Holy Spirit, in regeneration, sinful man cannot choose to follow God, nor does he desire to.
(Genesis 2:15-17, Romans 5:12, Psalm 51:5, 1 Corinthians 2:14, Romans 3:10-18, Jeremiah 17:9, John 6:44, Ephesians 2:1-10)
U– Unconditional Election teaches that in eternity past God choose to save His elect on the bases of His own Sovereign will. God’s election was not based on any foreseeable decision or response on behalf of an individual. God did not look down the corridors of time to see who would put their faith in him, and as he elected them. Instead, God chose to give his elect the gift of faith and repentance solely on the bases of His own grace and mercy. In the end, God choice of the sinner and not the sinners choice for God is the concluding end as to why all the elect respond to the gospel.
(Romans 9:10-21, Ephesians 1:4-11, Ephesians 2:4-10, Romans 8:29-30, Acts 11:18, Acts 13:48)
L– Limited Atonement teaches that the redeeming work of Christ was solely intended on behalf of all the elect. In eternity past, the Father gave the Son a particular people to redeem on the cross. Christ fully satisfied the wrath of God on behalf of the elect. Not only did Christ die for the sins of His people of the cross, but His death on their behalf also secured every needed for their salvation.
(Matthew 1:21, Romans 5:12-21, Romans 3:21-26, Ephesians 2:8-10, Titus 3:5-6, Philippians 1:6, John 10:11-30, John 17:6-12, Romans 8:28-30, John 6:44, Acts 20:28)
I– Irresistible grace teaches that all the elect will be irresistibly drawn to Christ. Those who once God haters and lived their lives rejecting Christ. Upon being awakened by the Holy Spirit by means of the external call of the preacher and the internal call of the Holy Spirit are now drawn to the beauty of Christ and by faith are compelled to believe on the Lord for salvation.
(John 3:16, Matthew 22:14, Acts 17:29-31, Matthew 23:37-39, John 6:44, Romans 8:28-30, John 1:12-13, John 3:1-8, Ephesians 2:8-10)
P– Perseverance of the Saints teaches that every person who has been chosen by the Father, Redeemed by the Son and drawn by the Holy Spirit and eternally secure in Christ and sealed by the Holy Spirit until the return of Christ. All those that are truly His will be kept until the end for Him and even though the righteous may fall in this life, they will ultimately never fall away from Christ.
(John 3:16, John 6:35-40, John 6:44, Philippians 1:6, Philippians 2:12-13, Jude 24-25, Ephesians 1:13-14, Romans 8:28-30, Romans 8:35-39)
For more study, please read: A BRIEF HISTORY OF THE DOCTRINES OF GRACE