‘The atonement is the work Christ did in his life and death to earn our salvation.’

A.  The cause of the atonement

1.  The love of God, Jn 3:16.
2.  The justice of God, Rom 3:25.

B.  The necessity of the atonement

This does not seek to answer the question ‘Why did God purpose to save any people at all?’  But rather, ‘Having purposed to save some, why was the death of Christ the only way this could be achieved?’
1.  The necessity of the atonement is indicated in Mt 26:39; Lk 24:25f.
2.  Rom 3:26 shows that the atonement was necessary in order to express and vindicate God’s moral character in being both just and justifier.
3.  Heb 2:17; 9:23-26; 10:4 show that there was no other way for God to save us.

C.  The nature of the atonement

The atonement is first of all objective: its primary influence in on God himself.  It is only secondarily subjective, having an application to us.

1.  Christ’s active obedience.  This is his life of perfect obedience to the law and will of God, Mt 3:15.

2.  Christ’s passive obedience.  This is his suffering and death which were necessary to pay the penalty for our sins.
(a) He suffered throughout his life, as in the temptation, Mt 4:1-11, and in the intense opposition he met from many Heb 12:3f.
(b) The pain of the cross.
(i) Physical pain and death
(ii) The pain of bearing sin, Isa 53:6; 2 Cor 5:21; Heb 9:28; 1 Pet 2:24. These passages teach that our sin was imputed to Christ.
(iii) Abandonment, Mt 27:46
(iv) Bearing the wrath of God, Rom 3:25.  This is propitiation.

3.  Further aspects of the death of Christ
(a) The penalty was inflicted by God the Father, Isa 53:6, 10; Rom 5:8; 2 Cor 5:21.
(b) Not eternal suffering but complete payment.  If we had to suffer for out own sins, the punishment would be eternal, and we still would not have atoned for them.  Christ’s sufferings, however, are complete and efficacious.  The penalty has been paid in full.  This stands in contrast to Roman Catholic teaching, which hold that the sacrifice of Christ is not merely commemorated, but repeated, in the Mass.
(c) The meaning of the blood of Christ.  The blood of Christ stands for his death viewed as a sacrifice for sin.  See 1 Pet 1:18f.  By the blood of Christ
(i) our consciences are cleansed, Heb 9:14
(ii) we gain access to God, Heb 10:19
(iii) we are progressively cleansed from indwelling sin, 1 Jn 1:7
(iv) we are able to conquer the accuser of the brethren, Rev 12:10f
(v) we are rescued from our sinful way of life, 1 Pet 1:18f.
(d) Christ’s death as ‘penal substitution’, or ‘vicarious substitution’

4.  New Testament terminology
(a) We deserve to die as the penalty for sin.  Christ died as a sacrifice, cf. Heb 9:26
(b) We deserve to bear God’s wrath against sin.  Christ died as a propitiation, cf. 1 Jn 4:10
(c) We are separated from God by our sins.  We are reconciled to God through Christ, 2 Cor 5:18f.
(d) We are in bondage to sin and to the kingdom of Satan.  Christ has redeemed us, Mk 10:45; Heb 2:15.

Based on Grudem, Systematic Theology, 568-580.