Only a Catholic can appreciate the fact that to love Mary is to Love the Lord even more. For our non-Catholic Christian brothers and sisters, here's a concise apology of our veneration (not worship) of Mary.
The first Eve was born of the rib of Adam to a preternatural perfection. She was the 'Mother of all the living.' Yet in her disobedience, seduced by the evil spirit, she gave birth to sin--bearing fruit in Cain the killer. Mary, the Second Eve, was born of the grace of the pierced side of Jesus Christ, in a God willed Immaculate Conception, to become the 'Mother of Mercy.' Through her obedience, humbly acquiescing to the holy angel, she gave birth to the Eternal Word of God, the Savior of mankind--bearing 'the fruit of thy womb' in Jesus. Mary is the Second Eve, as Jesus (attested to in the writing of St Paul) is the Second Adam. Mary's yes (fiat) to the angel is the hinge that opened the door for our salvation in Jesus Christ the Lord.
'For God so Loved the world' that He sent His Son to save us. Non-Catholic Christians won't argue that point. 'God alone is holy.' Another point of agreement. 'Jesus and the Father are One.' Agreement again. When God the Father (and the Holy Trinity) dwelt among the Israelites, He was carried in a venerated, adorned, ark. So too with His Son. God prepared the perfect(ed) vessel for the nine months of Immanuel's gestation in the Immaculate Conception of Mary. Nothing unholy could hold God but for a second. Mary, conceived without original sin, through the merits of her Son's Crucifixion and Resurrection, was 'full of grace' so that the 'Lord' would be 'with thee.' Mary, Immaculately Conceived, is the masterpiece of God's Creation--the obedient creature par excellence.
As the Jewish kings who lead to the King of kings had their mother as queen, so too Jesus, our King, has Mary as His Queen. In lieu of God's plan, Mary is Queen both of heaven (the saints and angels) and earth (in the Church Militant). Catholics believe, through apostolic witness, and centuries of Tradition, that Mary was Assumed, body and soul, shortly after her death, and received Queenly Coronation in heaven. Scripture states: 'A great sign appeared in heaven: A woman clothed with the Sun, and the Moon under her feet; and on her head a crown of twelve stars.'
Mary, moreover, is not just the mother of Jesus of Nazareth...but the Theotokos, or the Mother of God! If Jesus is truly the Son of the Living God, 'God from God, and Light from Light, begotten, not made,' then Mary, as His Mother is the Mother of God. And, as Jewish boys love their mother, as we all do, Jesus really loves His Mother!
In Genesis, in what is called the 'Proto-evangelium,' there is a mentioned enmity between the woman and the serpent. In the above mentioned Scripture passage with 'the woman clothed with the Sun,' she is stepping on the head of the serpent. That woman is Mary (and, yes, the Church) and that serpent is the devil. We must remember that Mary had free will. When she said yes to God in becoming Jesus' Mother, she acted freely, humbly, obediently, and became the 'Gate of Heaven.' Mary, therefore, is integral to our salvation, not as Savior--that is reserved to her Son--but as venerated servant, or handmaid of the Lord.
Finally, Mary, as best exemplified in the Rosary, both leads us to Jesus, and intercedes with the saints and angels on our behalf. In this 'vale of tears' she is a powerful intercessor always next to her Son, pleading our case in compassion and love.
And that is why we venerate (deeply respect) Mary.