But we are not people of fear, we are people of faith, the pastor added.
Meanwhile, a boy wounded in the shooting remains in critical condition in a hospital.
He was shot in the brain, officials said, but it remains unclear as to who shot him.
Joel OsteenAP
The incident sent worshippers rushing from the building between busy Sunday services, authorities said.
Police said the woman entered the church with a 5-year-old boy shortly before 2 p.m.
The woman began shooting, as officers at the scene engaged her and the woman was killed.
The 5-year-old was hit in the exchange of gunfire and critically injured.
Houston Police Chief Troy Finner said a 57-year-old man also was shot in the hip and wounded.
His condition is unknown.
Osteens televised sermons reach about 100 countries.
The Lord is our strength.