For a homogeneous material characterized by a conductivity $\sigma$ (in S/m) the resistance between any two points is unbounded. Such "infinite" resistance even applies if one point is replaced by a spherical surface centered around the point. Just check for yourself and calculate the resistance for this latter configuration by integrating $ 1/(4 \pi r^2 \sigma)$ from zero to any finite radial distance.
Physically what is happening is that the electrical field strength diverges towards a current injection point. You have to assume finite electrodes to obtain a meaningful answer.