Why do Christians always share their faith, even though it upsets people? It depends what motivates them

1. Do they believe they have to?
2. Do they think they are doing you a favor?

And he said unto them, Go ye into all the world, and preach the gospel to every creature. - Mark 15:16

For by grace are ye saved through faith; and that not of yourselves: it is the gift of God: Not of works, lest any man should boast. - Ephesians 2:8-9

Additional Reading: Ephesians 2:2-10