This is the post #28 of the Calvin's Institutes summary series.
It is not that the Law was contrary to the Gospel. The promises of redemption was already in the Law and Israel was meant to look forward to its revelation. In the Gospel, in the appearing of Jesus, we can see so much more clearly how God forgives and saves us through the Mediator. Similarly, we, Christians who believe in the Gospel are to still have hope because the final consummation of things is yet to come, just as under the Law, the Israelites were to have hope, waiting for the Mediator. It is wrong to think that we have already "arrived at the destination" (contra Servetus). All this is to say that we must not pit the Law and the Gospel against each other to the extreme. More will be explained in the next two chapters.