Can we have any hope that one who commits suicide does indeed place their trust in the finished work of Christ alone? Can a person, confident in God’s grace, hoping for His mercy, ever reach such a level of despair as to commit this grievous sin? Yes. While the faith which saves is sanctifying in us, it does not on this side of the veil finish the job. Any time any of us sin we are gainsaying our commitment to the gospel. We are implicitly affirming that our hope is in something other than Christ. That, however, is precisely why we need Christ – because we are sinners who place our hope in other things, because we are sinners who lose sight of His promises, because we are sinners who focus on our hardships rather than His provision.
R.C. Sproul Jr.