Was Timothy Paul's physical son, or what did Paul mean by calling Timothy his son in the faith?
Timothy was not Paul’s physical son. Paul called him my son in the faith, indicating a spiritual father-son relationship, not biological. Even though Timothy was in a different part of the world from Paul, Paul still referred to him as his son in the faith.
Les explains that when Paul calls Timothy “my son in the faith,” he means a spiritual relationship, not a physical one; Timothy was clear up in a different part of the world from Paul, yet Paul still called him his son in the faith. Paul uses the same term “sons” for the pagan Corinthian believers because he brought them the gospel and the salvation power that brought them out of paganism and idolatry. In verse 15, Paul notes they may have 10,000 instructors in Christ, but not many fathers—many Sunday school teachers, pastors, or television evangelists may teach, but only one or two usually have real impact in bringing a person to salvation.
For this cause have I sent unto you Timotheus, who is my beloved son, and faithful in the Lord, who shall bring you into remembrance of my ways which be in Christ, as I teach every where in every church.