The Rev. Wang Yijun is a Communist's headache, the kind of fellow who can spend 25 years behind bars and still remain bowed in prayer, presumably asking for the forgiveness of his jailers.

Yet he is also turning out to be a bit of a headache for some of the faithful.

After the police released the 75-year-old Father Wang last year, he celebrated Mass at the main Catholic church in this coastal city. That prompted several priests in the booming underground Catholic network to denounce him as a schismatic for giving legitimacy to the Government's pet church. They are now seeking his excommunication.

The episode underscores the tensions among Christians in China, as some of the faithful try to satisfy both conscience and commissar. Yet the incident also reflects the boldness and strength of an underground church that is thriving as never before.

One of the paradoxes of modern China is that Christianity may well be growing at a more rapid rate today, under a sometimes repressive Communist Government, than it ever did early in this century when missionaries were free to evangelize at will. 'Spring of Christianity'