The phrase "was existent" is grammatically correct and can be used in written English.
It is used to describe something that existed in the past, has since ceased to exist, or is no longer present. Here is an example: "The ancient civilization, believed to have been the most advanced of its time, was existent in this region over 2000 years ago."
Police officials were also angered by a remark by City Councilwoman Annette M. Robinson of Brooklyn, who said: "We looked at the officers that were on duty and wondered, if they were not in uniform, would they be the ones that participate in the kind of behavior that was existent in Central Park".
As formerly no coupling between reaction progress variable and enthalpy was existent, except through the temperature dependency of the laminar flame speed, an adaptation is proposed which offers an interface to initiate the combustion process.
In fact, this tax "hike" was not necessary a "hike" at all, but a return to the rate that was existent prior to the tax cuts proposed by the Bush administration.
The "radiating influence" theory (i.e., the Moon's light was light reflected from the Sun) was existent in Chinese thought from about the sixth century BC (in the Zhi Ran of Zhi Ni Zi), though it was opposed by the 1st century AD philosopher Wang Chong, who made clear in his writing that this theory was nothing new.
For PAD at least one of the following events was existent: significant ultrasound- or angiographically-proven vascular stenosis, percutaneous transluminal angioplasty, peripheral bypass or amputation.
For peripheral arterial disease (PAD) at least one of the following events was existent: significant ultrasound- or angiographically-proven vascular stenosis, percutaneous transluminal angioplasty (PTA), peripheral bypass or amputation.
Whatever is non-existent remains non-existent for ever and whatever is existent always exists.
Hence, God is existent, i.e. God exists.
Hence, the existent perfect being is existent.
Insofar as It is existent, the Principle is thus existent just as the world is.
Since the cause is existent, the effect also must exist.
