Yuri Samodurov and a colleague at Moscow's Sakharov museum were convicted on Monday and ordered to pay $3611 each for the Caution, Religion exhibition, which outraged many Orthodox Christians two years ago.
Two pictures - one showing Jesus' face superimposed on a soft drink logo and another giving visitors the chance to stick their face through an icon - were particularly controversial and the exhibition was vandalised by protesters.
Charges against the vandals were dropped after an outcry in parliament and the church, and Samodurov and his colleague were charged instead in a process Samodurov said showed how little independence Russian courts have.
"On one side of the scales was the court's legality and reputation, on the other was the judge's career and the pressure that was put upon him," the veteran activist, who was at the forefront of the human rights movement in late Soviet years, told Ekho Moskvy radio.
Apart from Caution, Religion, which was intended to show different interpretations of religion's role in Russian life, the Sakharov museum has held exhibits on themes such as the war in Chechnya that have outraged officials.
Reaction to ruling
The Orthodox Church, which 70% of Russians say they belong to, welcomed Monday's decision.
"People that insult religious and national sensibilities have to understand that in a civilised state punishment is inevitable," said a spokesman for the Moscow Patriarchate.
"Russian human rights activists are not financed by the people but by foreign grants. It looks like the activists will have to answer under the law for the insults they gave to their fellow citizens."
Lawyers for the two convicted museum workers said they hoped the decision would be overturned on appeal, but human rights groups said the court had already shown how far post-Soviet Russian courts were from protecting free speech.
"The conviction of Yuri Samodurov is an unacceptable restriction on freedom of expression," Rachel Denber of Human Rights Watch said in a statement.
"It sets a dangerous precedent for state censorship of art and public discussion."A Russian rights activist has been fined for inciting religious hatred by organising a controversial art show, a decision rights groups said showed how fragile the right to free speech remains in Russia.