"19 On the evening of that day, the first day of the week, the doors being locked where the disciples were for fear of the Jews, Jesus came and stood among them and said to them, “Peace be with you.” 20 When he had said this, he showed them his hands and his side. Then the disciples were glad when they saw the Lord. 21 Jesus said to them again, “Peace be with you. As the Father has sent me, even so I am sending you.” 22 And when he had said this, he breathed on them and said to them, “Receive the Holy Spirit. 23 If you forgive the sins of any, they are forgiven them; if you withhold forgiveness from any, it is withheld.”
24 Now Thomas, one of the Twelve, called the Twin, was not with them when Jesus came. 25 So the other disciples told him, “We have seen the Lord.” But he said to them, “Unless I see in his hands the mark of the nails, and place my finger into the mark of the nails, and place my hand into his side, I will never believe.”
26 Eight days later, his disciples were inside again, and Thomas was with them. Although the doors were locked, Jesus came and stood among them and said, “Peace be with you.” 27 Then he said to Thomas, “Put your finger here, and see my hands; and put out your hand, and place it in my side. Do not disbelieve, but believe.” 28 Thomas answered him, “My Lord and my God!” 29 Jesus said to him, “Have you believed because you have seen me? Blessed are those who have not seen and yet have believed.”
30 Now Jesus did many other signs in the presence of the disciples, which are not written in this book; 31 but these are written so that you may believe that Jesus is the Christ, the Son of God, and that by believing you may have life in his name."
John 20:19-31
Much can be learned from the record of Thomas’s doubting. The first thing that requires to be asked is, where was he, on that first Sunday? He was not in his place with the others: he should have been, and because he was not, he missed the blessing (this is one of the reasons why Hebrews 10:25 is important). Was he so despairing that he did not bother to come? It is true that sometimes the upsets of life lay such a hold on us that we feel we cannot come to Church; but Church is the very place for us, in such circumstances, for it is the place of blessing (cf Psalm 73:16,17). But there are other lessons here also, and one is our Lord's wonderful condescension to doubters. Thomas was clearly of a morbid temperament, and things often tended to take a darker hue for him than for others. It was probably this low spirit that had led to his absenting himself from the disciple band on the first occasion. This is certainly a spirit that can hinder and hurt the believer's life. But here is a word of great assurance: God is the God of doubters also, and He is willing to help and encourage us into light and peace out of our dark days. His loving-kindness can break through the midnight of the soul. Not only so, his dark doubt finally brought him to a wonderful confession of faith, 'My Lord and my God,' perhaps the greatest confession in the New Testament (we should notice in passing that Jesus did not contradict him, but accepted this testimony to His deity). From all this we may learn that those with early doubts, and many dark struggles, often by these very struggles, come through to bedrock faith and devotion. The fiery trial of faith in the crucible of darkness and affliction is not wasted. It is something to be brought through to this place!