The answer
God does not accept human sacrifice. This vow was definitely an error on Jephthah's part. His punishment for such a vow was clear: he had to sacrifice his one and only daughter. God did not accept this sacrifice but Jephthah felt he had to fulfill his vow. God did not ask Jephthah to offer Him a sacrifice. In contrast, God asked Abraham for the sacrifice. Abraham's faith was put under test and he succeeded in the test. Abraham's test was a test of obedience to God. We see that God did not go through with the human sacrifice but substituted it with a ram.St. Paul commends Jephthah for his faith in God when conquering the enemy, not for his vow and sacrifice. Other people of faith did sin against the Lord. However, they were still commended for their faith not for their sins. David was a man after God's heart yet he too had committed sin. Also the Spirit of the Lord came upon Gideon, but that did not prevent his erring in the matter of the ephod (Judg 8:27).
Answered by His Eminence Metropolitan Youssef (opens in a new tab)