As a Catholic worshiping in the Lutheran tradition I can tell you that Lutherans and catholics have more in common than they have differences. Yes, Lutherans have woman ministers, accept divorced and remarried at the table and do not say birth control is sinful but everything is grounded in Grace and service to others is primary and addressed in every LIturgy. ( Makes me think of Pope Francis!) God is the focus of worship and Scripture is a large part of the Liturgy. Lutherans believe in the real presence in Eucharist  and  as Catholics believe, it is a communal event (priests cannot say Mass alone). So why not celebrate our commonality and join each other in what we do believe together? By the way, Lutherans do not hold the differences 
Catholics do have against them but choose to dwell on what we believe in common.