John 20:29 Jesus said to him, Because you have seen Me, you have believed. Blessed are those who have not seen and have believed. 21:1 After these things Jesus manifested Himself again to the disciples at the Sea of Tiberias.
The Lord not only appeared to deal with the unbelief of Thomas but also to train the disciples to believe without seeing. The Lord was training them to practice His invisible presence. Because the Lord's presence in resurrection today is not a visible presence but rather an invisible presence, we must believe without seeing.
If we expect to see before we believe, we are wrong. We must practice believing without seeing because the Lord's presence now is not like it was when He was in the flesh. That was His visible presence.
Now that His presence is invisible, we must exercise our faith to realize it. Although we cannot see Him, we have the assurance that He is with us. Before His death, the Lord's presence was visible in the flesh.
After His resurrection, the Lord's presence is invisible in the Spirit. His manifestations or appearings after His resurrection were to train the disciples to realize, to enjoy, and to practice His invisible presence, which is more available, prevailing, precious, rich, and real than His visible presence. This dear presence of His is just the Spirit in His resurrection whom He has breathed into the disciples and who will be with them all the time.