Where is the scripture that says that the Church is the pillar and foundation of truth?

Question

And why was it written to Timothy?

Answer 1

1 Tim 3:15

"Ver. 15. The pillar and ground of the truth. By the promises of Christ to direct his Church by the infallible spirit of truth; (see John xvi. 7; Matthew xxviii. 20; &c. (Witham)) and therefore, the Church of the living God can never uphold error, nor bring in corruptions, superstition, or idolatry. (Challoner) --- That the Church, the pillar and ground of truth, is to be conducted by the constant superintendence and guidance of the Holy Spirit into all truth to the consummation of days, every one whose mind is not strangely prejudiced may easily discover in various places of the inspired writings."

Timothy had been sent by St. Paul the Ephesus to attack the false teaching that was being spread there. In this theme St. Paul was not only being encouraging but giving him the tools to fight the good fight.

In Christ
Fr. Joseph

Answer 2

The church is the body of Christ and is believers in all places over the earth