Why was the lay investiture a problem for the church?

Lay investiture was problematic for the Church because it allowed secular leaders to appoint bishops and other church officials, undermining the spiritual authority of the Church. This practice led to conflicts between the Church and state, as it blurred the lines between religious and political power. The Church sought to reclaim its independence and authority over spiritual matters, leading to significant tensions, such as those seen during the Investiture Controversy in the 11th century. Ultimately, the struggle highlighted the need for a clear separation between ecclesiastical and secular authority.