Fady, i play in church quite often and i think i understand your question. the problem is that "youth" songs tend to b written more for guitar, and you as a pianist are actually quite limited artistically. there may in reality only be a small amount you can do with the bass. when i play with the youth band, i tend to focus more on the right hand while the left hand just sustains the bass note for the chord. in the "adult" band, there are a lot more complex choruses and modernized hymns. for the more complex, piano driven songs, practice getting the left hand to match the syncopation in the right hand. also, the use of passing tones in the left hand helps to add variety to the sound.
hope this helped, good luck