Jesus' warning in today's gospel about whoever seems to have little it will be taken away, while to those who have, more will be given is understood in the context of the remarks about not lighting a lamp and placing it under a bushel basket or under a bed. It echoes the parable of the talents, wherein the servant who buried his talent had it confiscated upon his master's return.
Our faith is not meant to be hidden or stashed away for emergencies only. It is to be lived and to shine as brightly as we can burn. If we only have recourse to faith rarely and bury it away, we may find that it is extinguished entirely just when we need it most.