God is very concerned about our actions and how they affect others. Our own silly pride would lead us to believe that we can do as we please with no consequence. But God holds us accountable. God’s concern for causing another to stumble is first seen in His commands regarding our treatment of the poor and handicapped...
Do not curse the deaf or put a stumbling block in front of the blind, but fear your God. I am the LORD (Leviticus 19:14 NIV).
In other words, don’t ever stick your foot out in front of a blind person, or put something in his way that he could trip over, because he can’t see to defend himself. If we were to ever witness someone do that we would call that person a scoundrel. Yet, the same thing happens in New Testament churches among (so called) believers.
Therefore let us stop passing judgment on one another. Instead, make up your mind not to put any stumbling block or obstacle in your brother's way (Romans 14:13).
Every church has insincere people, or those with ulterior motives, who are a grief to everyone they come into contact with. Jesus said they are tares among wheat (Matthew 13:14-30). These hypocrites (Hupokrites – Greek for play-actor, a pretender, or one who outwardly goes through the motions which are insincere) become stumbling blocks to others... and ruin the faith of many. Such people will face a stern recompense from God Himself. Notice what Jesus said…
"Then He said to the disciples, It is impossible that no offenses should come, but woe to him through whom they do come! It would be better for him if a millstone were hung around his neck, and he were drowned in the depths of the sea, than that he should offend one of these little ones" (Luke 17:1-2).
Better to face capital punishment (execution) by drowning than to face God after having caused the faith of someone else to fail… by your own deliberate actions.
Gossip, slander, and backbiting qualify.