Matthew 28:20 - Jesus tells them: I am with you always
Luke 10:16 - speaks with Christs own voice
John 14:26 - Holy Spirit is to teach and remind them of everything
John 16:13 - guided by the Holy Spirit into all Truth
Acts 15:28 - Apostles speak with the voice of the Holy Spirit
1 Timothy 3:15 - Church is called the "pillar and foundation of truth"
1 John 2:27 - anointing of the Holy Spirit remains in you
St. Irenaeus (200AD) "For where the Church is, there is the Spirit of God; and where the Spirit of God is, there the Church and every grace is. The Spirit, however, is Truth." (Against Heresies 3, 24, 1)