Sincerity is one of the twelve attributes of the Mother.
Sincerity is compared to an atmosphere or a sheet of glass. If the one or the other is completely transparent, it lets light through without distorting it.
Similarly, a sincere consciousness lets divine vibrations through without distorting them.
The Mother – Some Answers from the Mother : CWM, Vol. 16, p. 382
“It is better to be than to seem. We do not need to appear to be good if our sincerity is perfect. And by perfect sincerity we mean that all our thoughts, feelings, sensations and actions should express nothing but the central Truth of our being.”
The Mother – Questions and Answers : CWM, Vol. 4, pp. 16-17
When you are absolutely sincere, you make a constant effort to live in harmony with the highest ideal of your being, the truth of your being. At every moment, in all that you think, all that you feel and all that you do, you try as perfectly as possible, as completely as possible, to put yourself in harmony with the highest ideal or, if you are conscious of it, with the truth of your being-then you have reached true sincerity….
The Mother – Questions and Answers : CWM, Vol. 4, p. 17
When someone has decided to consecrate his life to the seeking for the Divine, if he is sincere, that is to say, if the resolution is sincere and carried out sincerely, there is absolutely nothing to fear, because all that happens or will happen to him will lead him by the shortest way to this realisation.
The Mother – Agenda, Vol. 8, p. 151
Purity and sincerity are the same thing.
The Mother – Agenda, Vol. 5, p. 196
Before the Eternal Consciousness a drop of sincerity has more value than an ocean of pretension and hypocrisy.
The Mother – Words of the Mother – II : CWM, Vol. 14, p. 69