“Finitude includes doubt. The true is the whole (Hegel). But no finite being has the whole; therefore, it is an expression of the acceptance of his finitude that he accepts the fact that doubt belongs to his essential being.” (Tillich, ST 1, p. 10).
A text from the Epistle of Peter opened the service in the Middle Ages on the eight day after Easter. The day is therefore known by opening words of the Latin translation of the text: Quasi modo geniti infantes. Although the introitus would normally be chosen from the Psalms of the Old Testament, during Eastertide the text often came from the New Testament, like today:
“Like newborn infants, long for the pure, spiritual milk, so that by it you may grow into salvation— if indeed you have tasted that the Lord is good.”
Coming out of baptism at the Easter Vigil, the words would definitely make sense. That night the newly baptised Christian would partake in the Holy Eucharist for the first time, and they would certainly taste that the Lord is good (Ps. 34).
The day is also known as the day of the apostle Thomas (aram. twin), because he on the 8th day, according to the Gospel of John, met the risen Lord and believed. While Judas did not believe, Thomas, despite his doubts, came to believe that the Lord was risen and once again among his apostles. Paul Tillich has tried to stress the fact that somehow faith always includes doubt in some form or other. Doubt may be described as the twin of faith. Thomas is according to John 20:24 also called Dydimus (i.e. “Twin, called the twin”). What kind of doubt is it that Thomas displays? How can he be a help to the newborn Christian, barely come out of the baptism a week before? Thomas displays a curious and healthy scepticism that is required by all people of faith. It is a scepticism that is founded in trust as a basic phenomenon on one hand (the Lord is good!) and on the other hand the struggle to grow intellectually, spiritually and humanly. That is why the exhortation of Paul the apostle on leaving the childishness behind does not necessarily contradicts the word of Jesus Christ on becoming children.
To put it differently, Thomas’ doubt is not total doubt (Tillich, The Courage to Be, p. 48), which Tillich describes as existential despair. That is the way of Judas, not Thomas.