Religion is merely a means for the finite to approach the Infinite. Perfectly reasonable and appropriate when it's understood for it's purpose and limitations. When we decide however, that a certain man-made system is closer than others or -- even worse -- that ours is the Only Way because the Almighty said so, then we are flirting with dogmatism. As such it is blasphemy.
Of all the strange "crimes" that human beings have legislated out of nothing, "blasphemy" is the most amazing -- with "obscenity" and "indecent exposure" fighting it out for second and third place.Robert A. Heinlein, Time Enough for Love, 1973