The way for protestants and catholics to discuss matters of faith is to ask questions, and give honest answers, both done without accusation or condemnation.
protestant: why do catholics pray to mary and the saints?
catholic: because we want them to pray for us, to have more grace from God.
Their prayers are unhindered by earthly conditions. Also Mary is the Mother of God, so we believe she will present our prayers to Jesus, and that he will not refuse her.