We strongly reject, therefore, every explanation of the death of Christ which does not have at its centre the principle of ‘satisfaction through substitution’, indeed divine self-satisfaction through divine self-substitution.
The cross was not:
a commercial bargain with the devil, let alone one which tricked and trapped him;
nor an exact equivalent, a quid pro quo to satisfy a code of honour or technical point of law;
nor a compulsory submission by God to some moral authority above him from which he could not otherwise escape;
nor a punishment of a meek Christ by a harsh and punitive Father;
nor a procurement of salvation by a loving Christ from a mean and reluctant Father;
nor an action of the Father which bypassed Christ as Mediator.
Instead, the righteous, loving Father humbled himself to become in and through his only Son flesh, sin and a curse for us, in order to redeem us without compromising his own character.
The theological words ‘satisfaction’ and ‘substitution’ need to be carefully defined and safeguarded, but they cannot in any circumstance be given up. The biblical gospel of atonement is of God satisfying himself by substituting himself for us.
John Stott, The Cross of Christ (Downers Grove, IL: InterVarsity Press, 1986), 159-160.
(HT: Desiring God blog)