Seems clear to me from this verse that the living God is the pillar and foundation of the truth.
The church has made many errors; I doubt they are the absolute foundation of truth. LOL. God is.
...which is the church of the living God, the pillar and support of the truth. (New American Standard Bible)
...which is the church of the living God, the pillar and stay (the prop and support) of the Truth. (Amplified Bible)
...which is the church of the living God, a pillar and buttress of truth. (English Standard Version)
... After all, the church of the living God is the strong foundation of truth.(Contemporary English Version)
... which is the house of the living God. The church holds up the truth. (New Life Version)
Every Christian agrees that God is the Truth. ("I am the Way, the Truth and the Life.") But who or what supports the Truth? As you can see, all these translations refer to the the Church as the stay, prop, support, or buttress of the Truth.
I categorically deny that the Church has made doctrinal errors. Christ has promised that the gates of hell would not prevail against it.