How can the surface proteins of a capsid match receptors of its host cell?

if viruses are considered foreign invaders of a host cell, how could this come to be?

Viruses may, in some situations, have the ability to make protein structures mimicking those of a host cell. This may occur if that virus; or a predecessor of that viral particle has invaded a similar host cell in the past; and conveniently 'picked' up some of its surface-receptor-making-genes prior to destroying the host or budding off and moving to another. The newly formed viral particles therefore 'evolve' the ability to make the same host receptors by copying those genes every time they reproduce.