"But you, dear friends, must build each other up in your most holy faith, pray in the power of the Holy Spirit," Jude 1:20 NLT.
How do we build each other up? Jude 20 is often misconstrued to mean building each other up simply by praying in the Holy Spirit for one another. While that is true, it is only part of it. Jude was asking the believers here to build themselves up for the sole purpose of helping their churches better tackle the false teachers and their teachings, and to prepare them for Jesus' return. As such, he was not only referring to prayer but the knowledge of the word of God too.
Faith comes from hearing (the word) God. We build each other up by solidifying that faith through sharing the knowledge in word and praying for one another. I will say it again, we have gone past the time when someone could simply read the Bible on our behalf and just regurgitate them to you, no, each one of us has to become thirsty and come to the fountain of God's presence by ourselves and first for ourselves. After that, we can then better help other believers to stand in their faith.