In Judges 1, when Judah asked the Simeonites to help in the war against the Canaanites, isn't that considered as a lack of faith? God promised that Judah would win so why would he go looking for help?
Judah’s decision to align with Simeon to defeat the Canaanites could be seen as a lack of faith, since this was a time when every man did what was right in his own eyes.
On the other hand, Simeon lived entirely within the boundaries of the tribe of Judah so it makes sense that the tribe of Judah and the tribe of Simeon become allies in a conquest of the Canaanites in the region. Furthermore, the Lord never specifically commanded Judah to fight alone, so there's no evidence in Scripture to suggest that Judah’s decision to invite Simeon into the battle was a lack of faith.
For a complete explanation of this event, please listen to Lesson 1B of our Judges study.