  It has been shown that the negative-norm states necessarily appear in a
covariant quantization of the free minimally coupled scalar field in de Sitter
spacetime [1,2]. In this processes ultraviolet and infrared divergences have
been automatically eliminated [3]. A natural renormalization of the one-loop
interacting quantum field in Minkowski spacetime ($\lambda\phi^4$) has been
achieved through the consideration of the negative-norm states defined in Krein
space. It has been shown that the combination of quantum field theory in Krein
space together with consideration of quantum metric fluctuation, results in
quantum field theory without any divergences [4]. Pursuing this approach, we
express Wick's theorem and calculate M{\o}ller scattering in the one-loop
approximation in Krein space. The mathematical consequence of this method is
the disappearance of the ultraviolet divergence in the one-loop approximation.
