Are red snakes venomous

Not all snakes are venomous. Of the 3,500 snake species - only around 400 are actually venomous, AND of those, only a small number are actually lethal to humans !

There are around 650 venomous species with JUST Elapidaeand Viperidae. That's not including your venomous Colubrids (e.g. Boomslangs, Mangrove snakes, and other opisthoglyphs, though most rear-fanged snakes are of little to no consequence to humans, admittedly).