When Paul met with Peter, James the Lord’s half-brother, and John in Jerusalem, they found that ‘Paul’s gospel’ was exactly the same as ‘their gospel’.  That was because it was God’s gospel (Romans 1:1) - which He had revealed to all of them at different times and in different ways.  It was important for them to have that conversation; not only to encourage each other that what they believed and taught could only have come from God, but so that they could all refute the accusations of false teachers who said that Paul was preaching a different gospel.
 
Although Peter had no more apostolic authority than Paul, the Jewish believers thought he did; and they would be more likely to accept Peter’s assessment of Paul.  But the apostles knew that there was a difference between Paul and Peter – not in the content of their gospels, they were equally “servants of the Word” (Luke 1:1-2), but in their audience.  Peter was called to minister to Jews and Paul to Gentiles.  It was the same gospel to radically different cultural groups and God appointed different men to reach culturally dissimilar ‘people groups’.

Paul respected the opinion and fellowship of Peter, James and John but did not look to them to authorise his ministry.  Jesus had already done that.  However, their affirmation of the doctrine Paul was teaching was not only a mark of the divine origin of the gospel, and a bond of fellowship (Galatians 2:9).  It has also provided great reassurance for believers for 2000 years that there is only one gospel, authorised by Jesus, taught by the apostles.  That gospel of God’s grace through the substitutionary sacrifice of Jesus remains the only message which will bring eternal salvation to everyone who believes.  Those who deny it, add to it or subtract from it are presenting a false gospel which cannot bring eternal life (Galatians 1:6-9).
 
We are all ‘bit players’ in God’s great drama.  None of us can reach the whole world for Jesus, and He chooses different people to take His gospel to different people: some to another country, some to a professional group, some to men or women or children, some to socially despised people, some to governments and some to the sick.  It is a very important question for every believer to ask, ‘What people-group is God sending me to minister among?’  Of course Paul did also reach Jews, but his principal ministry was to Gentiles.  It will be the same with us; people in student ministries may also be used among the elderly.  But we need to be clear about our main ministry calling, so that we can invest our lives among the people to which God has called us, with humble confidence and boldness.  Ask the Lord and expect Him to guide you.