Brethren in Christ generally accept Mark 16:9-20 (the Longer Ending) as authentic Scripture, affirming it as part of Mark's Gospel. The passage includes Jesus's post-resurrection appearances, commissioning the disciples, and promising miraculous signs. For BIC, this passage reinforces the reality of the resurrection and the apostolic commission to spread the gospel.

The Longer Ending's emphasis on witness and mission aligns with Anabaptist conviction about the Great Commission. The promise of signs following believers (casting out demons, speaking in tongues, healing) has been interpreted within BIC tradition in light of the Holy Spirit's empowering presence for witness, though BIC is cautious about claiming all the specific phenomena listed.