Even best case scenario and he is a Christian and an Evangelist. There are still many red flags. Why does he want to marry a woman so much older than himself. My gut say's he is marrying for money or passport. Cross cultural relationships are incredibly difficult, I don't feel she is likely to have a sufficient understanding of Parkistani culture and life. By all means go and stay with his family and see if you can cope with the culture. Finally if he has a travelling ministry what happens if he is beaten up, arrested or murdered. I used to go to a Church which had links to a Parkistani church it was burnt down. Is she ready to be persecuted. Ask questions about how long she has known him encourage her not to rush into anything.
That's good advice.
I also think that the promise of a house, nice young christian man, family that loves her, fancy wedding all sound like bait to get her to go there.
Try to ask her questions, like, if he really loves you and knows about your family's concerns, don't you think he would want to reassure them? Why doesn't he come here first and you can meet in person here, and then he could meet your family as well. Wouldn't it be nice to get married knowing that your family is at peace with the decision? How do you know he is not meeting other women online? Have you checked the Pakistani laws to know what your rights are as a woman and as a married woman over there? Are you comfortable and at peace knowing that [insert all needed information here].
If she thinks their marriage is going to be a blessing to God's work, then she should know how that will be, but still, there is no need to feel rushed. She owes it to herself to check every little detail, especially since this sounds so much like a scam. Ask her, if her daughter were to announce to her the same, would she simply give her her blessings and be happy for her? Ask your government what their warnings are for women traveling and thinking of marrying someone from that country.
She should also find out how strong his faith is. Have her ask him questions about the Bible, or you could ask to meet him online, and when you do, ask him biblical questions and check how sincere he seems to be. This alone might be an eye-opener to her.