In these passages, Paul speaks of those who are weak in their Faith and those who are strong. The weak ones were afraid to eat meat. They only ate vegetables, thinking that avoiding meat was acting in obedience to God. Their belief was external and not internal.
They went through motions that we’re not motivated by strong belief in Jesus Christ. The strong believers did not have such restrictions in their diet, believing that all food was OK to eat. God had previously told the Apostle Peter this in a dream.
Paul said that strong believers should not put stumbling blocks before the weak believers. If they influenced weak believers to go against their conscience and eat meat, they would cause the weak believers to sin. The weak believer would be doing something he or she believed was wrong. This would be a sin.
Therefore strong believers have a responsibility to help their weak brethren. Even though the strong believers have freedoms to live their lives, they must not exercise these freedoms if doing so will cause their weak brethren to sin. Rather, the strong believer must ‘pursue the things which make for peace and the building up of one another.’