2 Timothy 2:15 Do your best to present yourself to God as one approved, a worker who has no need to be ashamed, rightly handling the word of truth.
When Paul tells Timothy to do his best to present himself to God as one approved, he doesn't leave it without explanation. What it means is that he is to work diligently in the text of the Scriptures so that he consistently and accurately holds to the truth of God. That word of truth is most applicably seen in the one and only gospel of Christ that alone brings salvation. There is too much at stake in the gospel for Timothy to do anything that may cause him to mishandle biblical truth and undermine its saving power. Given that we know this is the last letter of Paul, we can also be assured that Paul has tutored Timothy in the handling of Scripture in all the time they were spending on the road together. Timothy is Paul's beloved student. We can see the type of teaching Timothy may have received as Paul shows in his letters that the Old Testament consistently points to Christ.
The word, "approved" in the original Greek is dokimos. It means, tested. Timothy does not have to present himself to God to earn God's approval or favor. He already has that in Christ. He is to present himself to God as tested for ministry. That testing comes through his right handling of Scripture and its use in gospel ministry in the church he was pastoring in Ephesus.
When writing to the Thessalonians, Paul also says that he, Timothy and Silas were approved by God to be entrusted with the gospel. They had been tried and tested with gospel ministry as they taught from the authority of the Scriptures about Christ.
Being approved or tested by God may seem a vague concept to us. How do we know that our understanding of the Scripture makes us approved by God for gospel ministry? Timothy was told that this approval would mean that he would not be ashamed. No matter the difficult concepts in Scripture that warn of sin and judgment, Timothy would not skip the reality of those truths. Timothy would not be ashamed that among all the ideas of the world, the Scriptures alone have the one saving gospel. He would not be ashamed that salvation came through the shameful nature of a Roman cross. He would not be ashamed to stand on the only viable truth that the post crucifixion witnesses of Christ (including Paul) encountered a resurrected Lord. He would not be ashamed to point to the truth of the gospel to correct the self-interested false teachers around his church.
It takes diligence and boldness to be approved by God for gospel ministry. Who's up for it?