Despite the immaturity of the Corinthian church, its divisions, quarrelling, acceptance of immorality, confusion about marriage and how to live in a city dominated by pagan worship, Paul knew that many had held on to what he had taught them during his 18 month stay (Acts 18:1-18) and in a previous letter (1 Corinthians 5:9). Although he had to rebuke them, he also wanted to affirm those who had remained faithful to the truth.
 
The church was dysfunctional, but it was still a part of Christ's world-wide church. Messages had reached Paul about the state of the church (1 Corinthians 1:11; 16:17), but that many had stayed true to the gospel (1 Corinthians 15:1). So the Apostle encouraged them to continue to do what he had instructed (translated 'traditions' here).
 
Paul knew that the apostolic gospel must not be tampered with; it is complete and sufficient for salvation. Any additions or subtractions make it a false gospel which would lead people astray. So Paul was glad that they still held the true gospel, just as he passed it on to them. Of course, the gospel was not Paul's idea; he received it from the Lord (1 Corinthians 15:3; Galatians 1:11-12), and it was from the Lord that he received his apostolic responsibility (Romans 1:1-4). So the fact that many in the church still accepted Paul's teaching, was a mark of the Holy Spirit's work amongst them.
 
The gospel is constantly being challenged because it contains God's power to bring sinners to salvation (Romans 1:16). Change the gospel and the church is neutralised. And yet that is happening all over the world today. Some add what the apostles never instructed and others contradict what they clearly wrote. That is dangerously foolish because it strips the gospel of its power to convict sinners and lead them to repentance – without which there is no new life in Christ. A 'gospel' which is modified to suit personal preferences, immoral lifestyles, power lust, or reconstructed to make people happy by promising them what they want, is a false gospel: its teachers are under God's condemnation (Galatians 1:6-9). So, hold firm to the true gospel (2 Thessalonians 2:15) (www.crosscheck.org.uk). Revelation 3:11 quotes Jesus as saying, "I am coming soon. Hold on to what you have, so that no one will take your crown." It is that serious!