We can pray with confidence primarily because God is faithful to hear and answer our prayers. This belief is rooted in various religious texts and teachings that affirm God's willingness to listen to and respond to the prayers of His followers.
While being faithful followers is important and can strengthen our relationship with God, the assurance comes not from our own merit or the notion that we "deserve" to have our prayers answered, but rather from God's unwavering faithfulness and grace. God's nature and promises provide the foundation for our confidence in prayer, allowing us to approach Him with hope and trust.
In essence, our confidence in prayer arises from our understanding of God's character as loving, compassionate, and responsive to our needs and concerns.