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To curry favor in the hope of being accepted by a group, you might want to first establish your bona fides/bonafides.

To curry favor in the hope of being accepted by a group that has good or bad aims, you might want to first establish your bona fides/bonafides.

bona fides

1: good faith : sincerity
2: the fact of being genuine —often plural in construction
3: evidence of one's good faith or genuineness —often plural in construction
4: evidence of one's qualifications or achievements —often plural in construction
M-W

From the M-W entry for bona fide (adj.):

Bona fide also has the noun form bona fides; when someone asks about someone else's bona fides, it usually means evidence of their qualifications or achievements.

bona fides

1: good faith : sincerity
2: the fact of being genuine —often plural in construction
3: evidence of one's good faith or genuineness —often plural in construction
4: evidence of one's qualifications or achievements —often plural in construction
M-W

bona fides (n.) A person's honesty and sincerity of intention: he went to great lengths to establish his liberal bona fides.

[Treated as pl.] informal documentary evidence showing a person's legitimacy; credentials: are you satisfied with my bona fides?
[Origin: late 18th cent.] Latin, literally 'good faith.'
The New Oxford American Dictionary

Although examples of bonafides, the one-word form of the noun, can be found dating back at least 150 years, I've found no print or online dictionary that includes it.

From the M-W entry for bona fide (adj.):

Bona fide also has the noun form bona fides; when someone asks about someone else's bona fides, it usually means evidence of their qualifications or achievements.

bona fides (n.) A person's honesty and sincerity of intention: he went to great lengths to establish his liberal bona fides.

[Treated as pl.] informal documentary evidence showing a person's legitimacy; credentials: are you satisfied with my bona fides?
[Origin: late 18th cent.] Latin, literally 'good faith.'
The New Oxford American Dictionary