We may find it strange that Jesus didn’t consider qualities or skills Matthew had to offer but the calling the tax collector received was a sign of God’s mercy.
Firstly we can use the painting of Caravaggio “the calling of St Matthew” which faces us with profound meaning of the moment captured by the artist. At some close inspection we can discover that Caravaggio was inspired by the image of creation of Adam from Sistine Chapel, as the finger of Jesus Christ reaching out to Matthew is the same like the finger of God reaching out to the first man. Caravaggio expressed perfectly that calling to follow Christ means a new creation. When Jesus called Matthew he created him anew, Matthew was enabled not only to step out of his profitable business but he was enabled to step out of his self-interest and started imitating Jesus at serving others.
The same painting also shows us the surprise of Matthew who points at himself as if he were asking: “Are you sure that you want me to follow you?”
When we read the Gospel the ex-tax collector wrote we also discover that his calling wasn't simply mercy given him but his calling was also a sign of God's mercy for his people as trough St Matthew the Lord Jesus reached out to many other sinners.