“Faith is the infinite in man reaching out to join its source.”
I’ve been reading this statement of Rabbi Lichtenstein’s for over 30 years.
I confess to having been puzzled by it for all that time.
How can the “infinite” join “its source?” “Infinite,” by definition, has no source, no beginning, to join itself to. It’s its own source.
But, perhaps Rabbi meant the following:
We, ourselves, are made up of different levels. To say that “all is G-d,” or that “we are nothing but what G-d is,” etc., are accurate statements. This is the “higher Self,” the Divine Self, the “Image of G-d” of each of us. This is the infinite part of us that accepts all that happens with unchanging, calm bliss.
But each of us reflects that in a unique, finite way. This is our “small self,” our “animal soul.” This soul encompasses all of our thoughts, feelings and perceptions. In this soul is found our individual preferences — and the often fiery reactions when these preferences aren’t satisfied. Within this soul we might feel “loss” or “gain;” “winning” or “losing;” “better” or “worse.”
When we seek G-d in prayer or meditation, we sometimes — perhaps often — feel a degree of peace.
Yet, this might be no more than finding relaxation by simply postponing our satisfaction or temporarily distracting attention from our own demands.
Nor is the fullest peace gained by the “self” becoming aware of the actual presence of the “Self,” although this might be a first step.
The truest Peace is when we have left perception by the “self” behind, and begin perceiving with our “Self.”
“Awakening,” as it were.
“On the surface of life [i.e. of the mind], there is there is uncertainty and doubt; ambiguity and obscurity. [But]…below the surface, all is clear; all is revealed; there we behold the mighty Power from Whom all reality springs.” 
As Yishiyahu/Isaiah said:
יצר סמוך תצר שלום שלום כי בך בטוח
“Thou keepest him in perfect peace whose mind is stayed on Thee, for in Thee he trusts.”
Whose mind is kept on You, You keep in perfect peace.
That, I think, is what Rabbi Lichtenstein means to describe to us: The Infinite in us awakening to itself.
Our demands limit our attention only to our “self;” hold us back from the Peace that is “the Infinite in us.”
We open to the Infinite in us when we let go of our own preferences, our own concerns.
Better stated: It happens when G-d receives our preferences and concerns, after we have offered them — given them away — in moments of prayer and trust.
“When we give ourselves up to the contemplation of G-d, our soul takes us into a region beyond our present physical world…We transcend, we go beyond the limitation of finite thought, and we draw therefrom power, strength and wisdom …If we have been nervous, tense or worried, we can, in a few minutes, cause ourselves to become calm…It is a deliberate and conscious change from our daily thinking to a communication with the infinite, through our soul…It has been said that we can experience union with something larger than ourselves, a sense of oneness with the power beyond. In that union, we shall find our greatest contentment and peace. That union we make and can experience only through our soul.” 
This is the Peace that makes us prophets.
 Lichtenstein, Rabbi Morris; Jewish Science and Health; p. 136
 Yishiyahu/Isaiah 26:3
(I like the poetry of the King James translation; Wykoffe captures the repetition of “shalom” in his translation, but “perfect peace” captures the meaning, too)
 Lichtenstein, Rabbi Morris; Peace of Mind (“In the Silence”); p. 132
 Schwartz, Charles and Bertie; Faith through Reason; National Women’s League of the United Synagogue of America; 1946; p. 28-9