Adding commandments : (Romans 10:3), “For they being ignorant of God's righteousness, and going about to establish their own righteousness, have not submitted themselves unto the righteousness of God.” Jesus warned about following the commandments of men (Mark 7:6-13).
Worship of Mary, the mother of Jesus - Idolatry
Worshiping the Cross (idolatry)
Purgatory - Heresy about Hell
Teaching in an unknown tongue (Latin) (1 Corinthians 14:9)
Prayers directed to Mary or dead saints (Matthew 11:28; Luke 1:46; Acts 10:25-26; 14:14-18)
Treating the Pope as universal bishop (Jesus forbade headship to apostles (Luke 22:24-26; Ephesians 1:22-23; Colossians 1:18; 1st Corinthians 3:11)
Confessing of Sins to the priest (should be confessed directly to God (Read Psalm 51:1-10; Luke 7:48; 15:21; 1st John 1:8-9)
Bible Forbidden to be read by Laymen (Jesus wants scriptures to be read by All (John 5:39; 1st Timothy 3:15-17)
Modifying the cup in the communion: The Bible commands us to celebrate the Lord's Supper with unleavened bread and the fruit of the vine. (Read Matthew 26:27; 1st Corinthians 11:26-29).
The apocryphal books were added to the Bible (Not recognized by the Jewish Church)
The Immaculate Conception - Added to Catholicism while The Bible states that all men, with the sole exception of Christ, are sinners. Mary herself had need of a Savior. (Read Romans 3:23; 5:12; Psalm 51:5; Luke 1:30,46,47)