Could you give me a couple passages from the New Testament from which the substitutionary death of Christ is taught?
That Christ died in our place belongs to the very heart of the biblical understanding of the atonement. It is an attempt to unfold the meaning of Christ's death rather than a rational description of the process.
Possibly one of the most important passages on this subject is Jesus' words in Mark 10:45: "For even the Son of Man did not come to be served, but to serve, and to give his life as a ransom for many" (NIV). The term ransom designates the means of release or redemption and is associated with situations in which the life of the individual was in jeopardy (Ex. 30:12; Num. 35:31).
The idea of self-sacrifice in Mark 10:45 is defined as giving one's life for others. Here the Greek preposition "for" (antí) should retain its full substitutionary force: "in place of." The payment required from the many was their own lives. Yet they could not have ransomed themselves. They would have died. The only way out of their predicament was for someone else to die in their place. Jesus paid the penalty for their sins by giving His own life as their substitute.
The idea of substitution is strengthened in Isaiah 53 in connection with the words "give," "his life," and "many." If we consider the fact that Mark 10:45 contains a rather short saying, Isaiah 53 establishes the dependence of the one on the other.
Besides, conceptually the Servant dies in place of the many, bearing their sins. And in Mark the Son of man gives His life "in place of the many." In both cases God's instrument does something for the benefit of others, and the language of substitution unpacks the meaning of that action.
Paul also says that Christ "gave himself as a [substitutive] ransom [antílutron] for [hyper] all men" (1 Tim. 2:6, NIV). In this context Paul describes one of the ways in which Christ functioned as our mediator: He gave His life as a substitute—ransom—for the benefit of all. The mediator took the place of those who had been condemned.
Another important passage is Galatians 3:13: "Christ redeemed us from the curse of the law by becoming a curse for us" (NIV). First, the "curse" is the one pronounced by the Mosaic law upon its violators, and Paul argues that no one is capable of observing the Law completely (verse 10). Consequently the whole world is under the law and liable to receive its curse (verse 22).
Second, the law's curse was ordained by God Himself. It expresses a judicial action of God, the validity of which is not questioned, much less rejected, by Paul. Therefore, the curse of the law occupies a legal place in the human predicament on account of the universality of sin.
Third, the righteous claims of the law against sinners need to be fully satisfied. The curse could not be canceled out as if it never existed or ignored as irrelevant. This unavoidable phenomenon makes hopeless the plight of humanity and threatens its very existence. Without the legal claim of the law, the gospel becomes irrelevant and lacks purpose. This claim is to be satisfied, and this God did through Christ.
Fourth, Christ takes the curse upon Himself and dies in place of sinners on the cross. In this particular case the preposition "for" (hyper) contains the idea of substitution, because Christ became the recipient of the curse in our place, freeing us from its power. Although the word "satisfaction" is not used by Paul, the concept of substitutionary satisfaction is employed here. Love and justice are brought together in a mysterious way.
There is no clear attempt in the New Testament to explain in detail how this act of atonement took place in Christ. We are simply called to proclaim it. There is indeed a profound element of mystery in what took place on the cross and specifically in the transfer of sin and its penalty to the Son of God.
Contemplating this unfathomable act of divine love, Paul exclaimed, "The mystery of godliness is great" (1 Tim. 3:16).