GRAND RAPIDS, Mich. (AP) _ The 1985 Christian Reformed Church Synod has opened with the election of a Jenison minister as its president and expectation of a challenge to last year's admission of women as deacons.

''This synod will deal with some very difficult issues, especially regarding the role of women in church office,'' the Rev. Calvin Bolt of Jenison said Tuesday after he was chosen president of the 305,000-member church.

The convention, with 160 delegates from the United States and Canada, runs through June 21 at Calvin College.

Some conservative members are ready to challenge last year's decision to allow women deacons, Bolt said. About 100 women have since been ordained as deacons.

''I don't think this is a matter that will split the church, but I'm sure it will create a great deal of debate,'' Bolt said.

Other issues expected to be debated include statements on ministry to retarded people, use of liturgical dance, revision of the denomination's hymnal and the possibility of cutting ties with the two largest Reformed churches in South Africa over apartheid.