There is someone who steamrolls me every time and I never manage to say no. Afterwards I am furious, mostly at myself. How do I actually hold my ground?

“That Sanballat and Geshem sent unto me, saying, Come, let us meet together in some one of the villages in the plain of Ono. But they thought to do me mischief. And I sent messengers unto them, saying, I am doing a great work, so that I cannot come down: why should the work cease, whilst I leave it, and come down to you?”

Nehemiah's opponents invited him to a meeting on the plain of Ono, intending to harm him. His reply is a masterclass in refusal: I am doing a great work, so I cannot come down. No justification, no negotiation, no temper. They sent the same invitation four times and he sent back the same answer four times. A clear no, repeated without escalation, is a scriptural skill rather than a character flaw.

“But when Peter was come to Antioch, I withstood him to the face, because he was to be blamed.”

Paul describes withstanding Peter to his face at Antioch, publicly, because Peter had begun separating himself from Gentile believers under pressure from a visiting group. Paul does not go around him and he does not quietly seethe. The New Testament preserves the incident without pretending the early church was above conflict, and Peter later writes warmly about Paul. Confrontation between believers is not a failure of love here. It is an act of it.