I had a friend ask me why Catholics have Crucifixes in our churches...don't we believe Jesus has risen? Why do we keep Him on the cross?
First of all, you would want to check out 1st Corinthians, chapter 1, verse 23. Paul says, "...but we preach Christ crucified..." Why does Paul preach Christ crucified? Doesn't he know Jesus has been raised from the dead? Of course he does! But, he knows that it is through the power of the crucified Christ on the cross that the bonds of sin and death are broken. As Paul says in verse 24, Christ crucified is the "power of God".
1 Cor 2:2, "For I decided to know nothing among you except Jesus Christ and Him crucified." Again, didn't Paul know that Jesus had risen from the dead? Of course, he did.
Paul preaches Christ crucified because an empty cross has no power. The cross that bears the beaten, battered, and bloodied body of Jesus Christ, however, that cross is the "power of God". This is why, we "keep Jesus on the cross," because we, too, preach Christ crucified. The Crucifix reminds us not only of God's power, but also His love for us - giving His only begotten Son up for suffering and death.
Also, here in this life we do not share so much in the glory of the Resurrection, as we do in the suffering of Jesus on the cross; after all, we must take up our cross daily if we are to follow Jesus, as it says in Lk 9:23.
And, we must die with Christ in order to live with Him as Romans 6:8 tells us. Where did Christ die? On the cross. The Crucifix serves to remind us of these things.