5 We must therefore strive diligently that after beginning well we may also end well, that the counsels of God may be both understood and put in practice. The obedience shown to the Apostolic See will then be full and perfected, if it be joined with Christian virtue, and thus lead to the salvation of souls-the only end to be sought for, which will also abide forever. In the exercise of Our high Apostolic office, bestowed upon Us by the goodness of God, We have many times, as in duty bound, undertaken the defence of truth, and have striven to expound particularly those doctrines which seemed to be most useful to all, in order watchfully and carefully to avoid the dangers of error. But now, as a loving parent, We wish to address all Christians, and in homely words to exhort all to lead a holy life. For beyond the mere name of Christian, beyond the mere profession of faith, Christian virtues are necessary for the Christian, and upon this depends, not only the eternal salvation of their souls, but also the peace and prosperity of the human family and brotherhood.
Source: Exeunte Iam Anno (Vatican.va)