The Gospel Coalition published an excellent article this week written by Bryan Chapell. In the article, Chapell identifies four ways that all of the Bible points us to the Savior.
Take a few minutes to read through it, paying particular attention to his treatment of the topic of obedience toward the end.
Here's the "Cliff Notes" version:
1. Some passages—such as the prophecies and the messianic Psalms—clearly predict who Christ is and what he will do.
2. Other passages prepare God’s people to understand the grace God must provide to redeem them.
3. Because grace is the key to understanding God’s purposes, culminating in Christ, aspects of the gospel are reflected throughout Scripture.
4. We understand how God’s redemptive message appears in Scripture through texts that result from Christ’s work on our behalf.