In 1 Cor 15-54 Saint paul states that the Church in heaven and the Church on earth are one. If therefore I can ask you as a brother or sister to pray for me here on earth why can I not ask you to intercede on my behalf in heaven?
To say that we as Christians and specifically as Catholics worship Saints is to be ignorant of our teaching. As Christians we worship and declare the one true God within the mystery of the Holy Trinity.
To ask a saint to pray for us is to acknowledge that an individual lives on in Christ after death, in fact it is a testimony to this reality. Those who are declared Saint by the Catholic Church are also examples of how God can transform and use an individual. When we read the lives of the Saints, we learn ways in which we can co-operate with God in every age.
As Catholic/Christian we hold onto what Paul relates as 'the sure hope of salvation. There are other Christian that believe that one is saved from the moment they acknowledge Jesus as Lord of their life. This fulfills two of the three pillars of Christian faith. Namely Faith and Love.
Catholics on the other hand believe in three pillars of faith - 'Faith, Hope and Love. We believe that one can deliberately with their free will choose to sin and separate themselves from God at any time during their Christian life - they can also choose to repent and this is why we have the sacrament of reconcilliation.
The Christian life is not easy to live, we need the support of the Holy Spirit and of our brothers and sisters in intercessory prayer both when they live as Church here on earth and most especially as they continue to live as Church in Heaven.
I have discovered that those who misunderstand how Catholics understand the saints have not taken the time to study our teachings. We do not pray to the dead we pray with the living on earth and in Heaven.