This article presents the first computation of the complete bispectrum of the cosmic microwave background temperature anisotropies arising from the evolution of all cosmic fluids up to second order, including neutrinos. Gravitational couplings, electron density fluctuations and the second order Boltzmann equation are fully taken into account. Comparison to limiting cases that appeared previously in the literature are provided. These are regimes for which analytical insights can be given. The final results are expressed in terms of equivalent f_NL for different configurations. It is found that for moments up to ell_max = 2000, the signal generated by non-linear effects is equivalent to f_NL simeq 5 for both local-type and equilateral-type primordial non-Gaussianity.