i think you should say 我仍然相信爱 信仰 refers to someone or some idea, religious or extreme trust and respect God, resulting thoughts and feelings of awe and worship, used as a model or guide their actions. In summary, the belief is a human right of life, values and world view and choice and hold.

应该是我还是相信爱~信仰是对某种主张、主义、宗教或某人极其相信和尊敬

相信 - believing ( in love ) 信仰 - worship ( to the god)

i agree with 毛天一 Tiffany and Mr.Bean, i guess you should say "我仍然相信爱" but when you say " I believe in love", if you want to emphasize "believe"(not love), then you may (maybe) mean "我信仰爱" if you saw a british film "a man for all seasons" once, you may remember Thomas More and Duke of Norfolk's conversation, Thomas More said "believe" twice if you trust something just because you think it's real or it will happen, use "相信". if believing in something means very special and important to you, like a christian believe in Jesus, then you have to use "信仰" i have to say that i can not agree with Janeliu's answer at all, apparently it's absolutely wrong.

若無上下文 而逕自斷章 逐字翻譯 就會出現取義的問題 我會譯成：『愛就是堅信不渝』 視說話人的身分 場合而定 若是情侶情意纏綿時 就解為 『相信』 若是宗教家莊嚴佈道時 就解為 『信仰』