8. The expression “most holy faith” may have referred to what?

⁸ Jude next turned to earnest entreaty, saying:

“But you, beloved ones, by building up yourselves on your most holy faith, and praying with holy spirit,

Jude 20,

Jude lovingly showed how his cherished fellow believers could remain in the love of Jehovah. Following his counsel certainly would include the cultivating of faith, a fruit of God’s spirit. (Galatians 5:22, 23) But in view of Jude’s earlier reference to fighting for ‘the faith delivered to the holy ones’ (Jude vs. 3), the expression “most holy faith” may have referred to the whole range of Christian teachings, including the good news of salvation. The foundation of such true faith is Christ, and it was called “most holy” because it looked to the God of holiness and was based exclusively upon his holy Word.​—Acts 20:32; 1 Corinthians 3:10-15.

9. We must do what to ‘upbuild ourselves on our most holy faith’?

⁹ For Christians to ‘upbuild themselves on their most holy faith,’ or to strengthen it, they must diligently study God’s Word personally and congregationally. Frequently discussing the Scriptures with fellow Christian witnesses of Jehovah, as well as proclaiming the good news to others, will deepen the impression the Bible makes on our hearts. But none of this can be accomplished apart from earnest prayer. An individual ‘prays with holy spirit’ when praying under its influence and in harmony with the things in Jehovah’s Word. Moreover, the Scriptures, written under inspiration of God’s spirit, show us how to pray and what to request in prayer. For instance, we can confidently pray to be filled with God’s holy spirit. If we ‘pray with holy spirit,’ our prayers will reveal a proper heart condition, one loved by God. We will thus be protected from improper influences, including the views of any “ungodly men” who might slip into the congregation.​—Luke 11:13; Romans 8:9, 26, 27.