Faustus doesn't necessarily not believe in the reality of repentance, and he is quick to realise that it is too late for repentance however much he might wish for it in Act V. However, his problem is that at every stage he has the opportunity to repent, he is tempted to continue in his path towards damnation, choosing to blind himself or allowing himself to be persuaded that he does not need to worry about repentance at that stage. Act II scene 1 is a classic example of this in practice. The Good Angel and the Evil Angel both try and vie for power within Faustus, with the Good Angel urging him to repent. The Evil Angel, however, tells Faustus to think of "honour and wealth" instead of "heaven and heavenly things." Note how Faustus responds to this prompting:
Why, the signiory of Embden shall be mine.
When Mephistophiles shall stand by me,
What power can hurt me? Faustus, thou art safe:
Cast no more doubts.
Faustus therefore allows the temptations of the Evil Angel to help him ignore the state of his soul and the eternal repercussions of his actions. As the statement in this question suggests, he allows the various temptations of power and wealth that he has to persuade him that he is "safe," and he has no need to doubt any more. Even though Faustus is well aware of the consequences of his actions, what is seen in this quote is the way he deludes himself because of the fleeting temptation of power and its enjoyment in the here and now. This is of course something that he later regrets when it is too late.