Paul's first epistle to Timothy is all about his work in the ecclesia at Ephesus. He opens with a prayer for Timothy's spiritual well-being

Although we know little of Timothy's personal life, he is the best known and closest of Paul's fellow-laborers. He was brought into the Truth by Paul and is referred to as Paul's "own son in the Faith." He joined Paul's company on Paul's second journey, and worked with him thereafter till the end of Paul's life.

His father was a Gentile, and Timothy was not circumcised, although he knew the Holy Scriptures from childhood.

His mother and grandmother were faithful believers, but his father and grandfather were not so mentioned. It would appear from this that faithfulness was on the female side of the family, and probably against difficulties. 

Timothy's mother may have been given in marriage to a Gentile by her father, against her own mother's wishes. *

* Bro Growcott - Grace, Mercy and Peace from God.