It's the one Jesus began and the one into which He will reunite all those that are His who currently attend offshoots of that church (denominations).

There is not one true Church, many, in fact most Churches do preach the truth, but they do it in different ways. Christians are united in faith, but not in expression. Some people are more comfortable with an Orthodox Liturgical service and some are the "Happy/Clappy" Pentecostal types. Some, like myself, are somewhere in the middle.