Muslims don't deny the importance of Jesus, they just don't place Jesus on the same level or above God--Thy shall have One Lord thy God. For even Jesus(pbuh) said: Worship God alone & God is greater than I.
Jesus prayed to God(The One and Only Creator, Creator of Jesus, of you & me and everything in existence) so why do you pray to Jesus? Or to Mary? Or to the saints? Or to the cross? How is that monotheism?!