“But you, beloved, building yourselves up in your most holy faith and praying in the Holy Spirit, keep yourselves in the love of God, waiting for the mercy of our Lord Jesus Christ that leads to eternal life.”  –Jude 1:20-21

The grace of faith is most holy, as it works by love, purifies the heart, and overcomes the world, by which it is distinguished from a false and dead faith. Our prayers are most likely to prevail, when we pray in the Holy Ghost, under his guidance and influence, according to the rule of his word, with faith, fervency, and earnestness; this is praying in the Holy Ghost. And a believing expectation of eternal life will arm us against the snares of sin: lively faith in this blessed hope will help us to mortify our lusts.

–Matthew Henry’s Commentary