Some friends and I have been invited to a Christmas concert at our friend’s Evangelical church. We are all practicing Catholics. One of our friends, who is Catholic, is undergoing chemotherapy and will be with us at the concert. At the end of the concert they ask you to come up and pray with their pastor (an altar call). Our Evangelical friend insists that our sick friend should go up and be prayed over and a priest friend of mine told me that she should not go up for an altar call since she is Catholic. What should we do?
An "altar call" is different than an invitation to be prayed over for illness. An "altar call" is an invitation to "accept Jesus as your personal Lord and Savior," essentially by dropping your Catholic understanding of how salvation works. That is probably why the priest advised against responding to an altar call.
That said, if your Evangelical friend is "insisting" that your ill friend must go up and be prayed over at this service, despite her own reservations against doing so, then I strongly advise that all of you who are Catholic decline to attend this event. It is obviously being used as a means of proselytism to the attendees under the guise of a Christmas concert.