Sequence of Verses
Warnings of punishment against disbelief (kufr) - whether original or apostacy (irtidad) - appeared in previous verses. After that, in the first (106) of the initial three verses cited above, it has been pointed clearly that 'Iman or the declaration of faith is a wealth that could work wonders for a kafir (disbeliever) or murtadd (apostate) who - if he were to come up with an honest and true 'Iman - all his past sins would stand forgiven.
In the second verse (107), the last day of Qiyamah was mentioned for the reason that all this phenomena of reward and punishment has to occur after that. In the third verse (108), it was said that the real punishment of disbelief and sin will, though come after the Qiyamah, yet there are some sins the punishment of which is faced in a certain degree within the present world.