ateist

/ateist/

Cases

SingularPluralWhen to use it
nominativeateistthe atheistateistlethe atheiststhe plain dictionary form — the doer of the sentence
genitiveateistnithe atheist'sateistlenithe atheists'the owner — whose it is
accusativeateistnithe atheist (as the object)ateistlenithe atheists (as the object)a specific, known object — whom or what
dativeateistgeto the atheistateistlegeto the atheistsdirection or recipient — to where, to whom
locativeateistdeat / in the atheistateistledeat / in the atheistswhere it is; also having — mende bar, "I have it"
ablativeateistdenfrom the atheistateistledenfrom the atheistswhere it comes from; also "than" when comparing
When to use each case
nominative
the plain dictionary form — the doer of the sentence
genitive
the owner — whose it is
accusative
a specific, known object — whom or what
dative
direction or recipient — to where, to whom
locative
where it is; also having — mende bar, "I have it"
ablative
where it comes from; also "than" when comparing

The endings are the same ones the pronouns wear — that page explains when each case is used.

With an owner

One ownedSeveral owned
myateistimmy atheistateistlerimmy atheists
yourateistingyour atheistateistleringyour atheists
his / herateistihis / her atheistateistlerihis / her atheists
ourateistibizour atheistateistleribizour atheists
you all'sateistigizyou all's atheistateistlerigizyou all's atheists
theirateistleritheir atheistateistleritheir atheists

The overlap in the last rows is real, not a mistake: ateistleri can mean "his / her atheists", "their atheist", or "their atheists" — context decides.