In Romans 14:2 it becomes evident what kind of weakness in the faith Paul is referring to in Romans 14:1. Faith in Christ means being liberated from any obligation to observe any dietary law or taboo, regardless of whether it originates from the Jewish or the Gentile tradition, and regardless of the superstitions involved. Faith frees people from the bondage of ancestral habits and customs as well as from the fear of superstitions. Unburdened by these, the children of God give thanks and eat all that the Creator gives (1 Timothy 4:4–5). This is an extraordinary course of action especially for Jews (see Acts 10:1–48), but also for Gentiles, who were themselves burdened by many rules regarding what food was permitted and what was not.1
1 As for the one who is weak in faith, welcome him, but not to quarrel over opinions.