Actually, no it doesn't. It is taking God at his word.
John 3:18 He who believes in Him is not judged; he who does not believe has been judged already, because he has not believed in the name of the only begotten Son of God.
Actually, yes it does. At the moment of your death, will you believe in God? You cannot say that until then. And if you go back to the Greek, the word is condemned, not judged, I believe. I will ask Kosta to confirm. And if belief is required, then the process of purgatory will set in according the Judgement of deeds.
The word is “krino” and means:
1) to separate, put asunder, to pick out, select, choose
2) to approve, esteem, to prefer
3) to be of opinion, deem, think, to be of opinion
4) to determine, resolve, decree
5) to judge
a) to pronounce an opinion concerning right and wrong
1) to be judged, i.e. summoned to trial that one’s case may be examined and judgment passed upon it
b) to pronounce judgment, to subject to censure
1) of those who act the part of judges or arbiters in matters of common life, or pass judgment on the deeds and words of others
6) to rule, govern
a) to preside over with the power of giving judicial decisions, because it was the prerogative of kings and rulers to pass judgment
7) to contend together, of warriors and combatants
a) to dispute
b) in a forensic sense
1) to go to law, have suit at law
Scripture promises that the elect will not be deceived, and He will keep them secure
Point us at the purgatory scripture?
Depends. The word itself (krino) is not really legalistic; it's primary meaning is to set aside, put asunder, whether it is for praise or for condemnation or for any other reason.
The problem is not so much with verse 18 but with verse 15, which has been corrupted (doctrinally altered) in later copies.
The verse thus reads "That whosoever believeth in him should not perish, but have eternal life" but the older copies read "so that whoever believes will in Him have eternal life."
Clearly, there is no judgment here but simply a consequence of one's faith: those who believe are promised a reward of eternal life in Christ.