Let's now look at a second issue Roman Catholic teachings - the veneration of Mary. If you don't believe that they place her in a position that was not meant for her, please look at the following prayer.
Hail Holy Queen
Hail, Holy Queen, Mother of mercy, our life, our sweetness, and our hope. To thee do we cry, poor banished children of Eve. To thee do we send up our sighs, mourning and weeping in this vale of tears. Turn then, most gracious advocate, thine eyes of mercy towards us and after this, our exile, show unto us the blessed fruit of thy womb, Jesus. O clement, O loving, O sweet Virgin Mary. Pray for us, O holy Mother of God. That we may be made worthy of the promises of Christ.
From this prayer, we see that they place her as an advocate between us and Jesus, as well as between us and God. Let's look at this next scripture to see if this lines up with the Bible, which is what we are supposed to do with anything we hear. "For there is one God, and there is one mediator between God and men, the man Christ Jesus." (1 Timothy 2:5) It is clearly seen that they have made an extremely large mistake here. It goes against the Bible that they say they believe. Now, whether it is the (false) teachings of Roman Catholicism or any other religion, we must refute it with the truth. We do this in the manner as it states in 2 Timothy 2:24-25, “And the Lord's servant must not be quarrelsome but kind to everyone, able to teach, patiently enduring evil, correcting his opponents with gentleness. God may perhaps grant them repentance leading to a knowledge of the truth.”
I pray that this is an encouragement to you all to witness to others, even if they say they are Christian (whether Catholics, Mormons, JWs, …) They may not truly know about the heresy being taught to them. There are many other things that we could look at, such as Catholics believing that their works help save them (rather than being saved by grace, through faith, in Christ ALONE). However, I believe these two are enough to start a conversation with a Catholic (which I continually do!) Do it gently and with the Bible in your hand, so that you can easily open up the scriptures with them. Remember Luke 10:2, "And he said to them, 'The harvest is plentiful, but the laborers are few. Therefore pray earnestly to the Lord of the harvest to send out laborers into his harvest.'"