en_tn_condensed/1ti/02/07.md

For this purpose

"For this" or "For this reason"

I was appointed a herald and an apostle

This can be stated in active form. Alternate translation: "Christ appointed me to be a herald and an apostle" or "Christ made me a preacher and an apostle" (See: rc://en/ta/man/translate/figs-activepassive)

a herald

"an official messenger." A herald is an official messenger who is sent to bring news.

I am telling the truth, I am not lying

With these two comments Paul emphasizes that he is telling the truth when he says that he was appointed to be a herald, an apostle, and a teacher. Some translators may prefer to put these comments at the end of the verse.

in faith and truth

This probably refers to what Paul was to teach about. He may be using "faith" and truth" to express one idea. Alternate translation: "about the message of faith and truth" or "about the true faith" (See: rc://en/ta/man/translate/figs-hendiadys)