Unless you're willing to say that true Christians never knowingly sin, then you have to answer the title-question "Yes." Every time a Christian knowingly sins, that Christian has broken out from under Christ's yoke. If surrender to Christ's Lordship was an automatic, constant, and unchangeable result of being born-again, then Paul had no good reason to write us Romans 12:1, or Peter to write us 1 Peter 3:15a.
Jack is the teaching elder of Ironworks Pike Community Church. He is a graduate of Columbia Biblical Seminary http://www.ciu.edu.