If what we’re depending on has the potential to fail us, then we’re on unstable ground. Only God is never failing, so if we depend on him, we can be sure that all things will work together for good.
Much of the work to spread the gospel at home happens before one ever returns there: learning to own the great commission, getting equipped, and allowing the Lord to fitly join you to your local church that can continue to be a support when you return home.