Your sentense reads:
Our aim is to help people discover, and grow in, faith in Jesus Christ.
The way you have used commas just sets of "and grow in". Consequently, your sentence reads like this without that "and grow in":
Our aim is to help people discover faith in Jesus Christ.
However, I guess you wanted to help people to both "discover" and "grow in" faith in Jesus. If that is your objective, you may say:
Our aim is to help people discover and grow in faith in Jesus Christ.
Then, there is a small problem that the sentence does not sound well. The reason is that you have combined asymmetrical entities, viz. "discover" and "grow in" using "and". In order to get rid of that problem, you may reconstruct the sentence.