59 Realizing the many difficulties of the present hour and knowing that membership in the party and the oath are for countless persons a necessary condition of their career, of their daily bread, and even of their life itself, We have sought to find a way which would restore tranquillity to these consciences, reducing to a minimum the external difficulties of the situation. It seems to Us that such a means for those who have already received the membership card would be to make for themselves before God, in their own consciences, a reservation such as "Saving the laws of God and of the Church" or "In accordance with the duties of a good Christian," with the firm proposal to declare also externally such a reservation if the need of it arose.
Source: Non Abbiamo Bisogno (Vatican.va)